1. MySQL's optimizer can recognize expressions:

mysql> create table t1 (a int, b int, c int  generated always as (a+1));
mysql> alter table t1 add key(c);
mysql> insert into t1 (a,b) select a,a from one_k;
mysql> explain select * from t1 where (a+1) =1;
+----+-------------+-------+------------+------+---------------+------+---------+-------+------+----------+-------+
| id | select_type | table | partitions | type | possible_keys | key  | key_len | ref   | rows | filtered | Extra |
+----+-------------+-------+------------+------+---------------+------+---------+-------+------+----------+-------+
|  1 | SIMPLE      | t1    | NULL       | ref  | c             | c    | 5       | const |    1 |   100.00 | NULL  |
+----+-------------+-------+------------+------+---------------+------+---------+-------+------+----------+-------+
1 row in set, 1 warning (0,00 sec)

mysql> explain select * from t1 where (a+1) <1;
+----+-------------+-------+------------+-------+---------------+------+---------+------+------+----------+-------------+
| id | select_type | table | partitions | type  | possible_keys | key  | key_len | ref  | rows | filtered | Extra       |
+----+-------------+-------+------------+-------+---------------+------+---------+------+------+----------+-------------+
|  1 | SIMPLE      | t1    | NULL       | range | c             | c    | 5       | NULL |    1 |   100.00 | Using where |
+----+-------------+-------+------------+-------+---------------+------+---------+------+------+----------+-------------+
1 row in set, 1 warning (0,00 sec)

mysql> explain select * from t1,ten where (t1.a+1)=ten.a;
+----+-------------+-------+------------+-------+---------------+---------+---------+------+------+----------+--------------------------------------------+
| id | select_type | table | partitions | type  | possible_keys | key     | key_len | ref  | rows | filtered | Extra                                      |
+----+-------------+-------+------------+-------+---------------+---------+---------+------+------+----------+--------------------------------------------+
|  1 | SIMPLE      | ten   | NULL       | index | PRIMARY       | PRIMARY | 4       | NULL |   10 |   100.00 | Using index                                |
|  1 | SIMPLE      | t1    | NULL       | ALL   | NULL          | NULL    | NULL    | NULL | 1000 |   100.00 | Using where; Using join buffer (hash join) |
+----+-------------+-------+------------+-------+---------------+---------+---------+------+------+----------+--------------------------------------------+
2 rows in set, 1 warning (0,01 sec)

#2. But join queries are not recognized

create table t0 as select * from ten;
alter table t0 add primary key(a);
alter table t0 add b int;

mysql> explain select * from t1,t0 where (t1.a+1)=t0.b and t0.a=1;
+----+-------------+-------+------------+-------+---------------+---------+---------+-------+------+----------+-------------+
| id | select_type | table | partitions | type  | possible_keys | key     | key_len | ref   | rows | filtered | Extra       |
+----+-------------+-------+------------+-------+---------------+---------+---------+-------+------+----------+-------------+
|  1 | SIMPLE      | t0    | NULL       | const | PRIMARY       | PRIMARY | 4       | const |    1 |   100.00 | NULL        |
|  1 | SIMPLE      | t1    | NULL       | ALL   | NULL          | NULL    | NULL    | NULL  | 1000 |   100.00 | Using where |
+----+-------------+-------+------------+-------+---------------+---------+---------+-------+------+----------+-------------+
2 rows in set, 1 warning (0,00 sec)


# 3. in the trace, it is "substitute_generated_columns"

mysql> explain select * from t1 where (a+1) <1;

          {
            "substitute_generated_columns": {
              "resulting_condition": "(`t1`.`c` < 1)"
            }
          },

# 4. What if there are multiple ways one can substitute? 

mysql> alter table t1 add column c1 int generated always as (a+1);
mysql> alter table t1 add index(c1, b);

mysql> show create table t1;
CREATE TABLE `t1` (
  `a` int DEFAULT NULL,
  `b` int DEFAULT NULL,
  `c` int GENERATED ALWAYS AS ((`a` + 1)) VIRTUAL,
  `c1` int GENERATED ALWAYS AS ((`a` + 1)) VIRTUAL,
  KEY `c` (`c`),
  KEY `c1` (`c1`,`b`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;


mysql> explain select * from t1 where (a+1) =1 and b=2;
+----+-------------+-------+------------+------+---------------+------+---------+-------+------+----------+-------------+
| id | select_type | table | partitions | type | possible_keys | key  | key_len | ref   | rows | filtered | Extra       |
+----+-------------+-------+------------+------+---------------+------+---------+-------+------+----------+-------------+
|  1 | SIMPLE      | t1    | NULL       | ref  | c             | c    | 5       | const |    1 |    10.00 | Using where |
+----+-------------+-------+------------+------+---------------+------+---------+-------+------+----------+-------------+
1 row in set, 1 warning (0,00 sec)

mysql> explain select * from t1 ignore index (c) where (a+1) =1 and b=2;
+----+-------------+-------+------------+------+---------------+------+---------+-------------+------+----------+-------+
| id | select_type | table | partitions | type | possible_keys | key  | key_len | ref         | rows | filtered | Extra |
+----+-------------+-------+------------+------+---------------+------+---------+-------------+------+----------+-------+
|  1 | SIMPLE      | t1    | NULL       | ref  | c1            | c1   | 10      | const,const |    1 |   100.00 | NULL  |
+----+-------------+-------+------------+------+---------------+------+---------+-------------+------+----------+-------+
1 row in set, 1 warning (0,00 sec)