create table t2(a int);

insert into t2 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);

create table t1 (key1 int, col1 int, key(key1));

insert into t1

select A.a + 10 * B.a + 100 * C.a, 1234 from t2 A, t2 B, t2 C;

mysql> explain update t1 set key1=key1+1 where key1 between 10 and 110 order by key1 limit 2;

+------+-------------+-------+-------+---------------+------+---------+------+------+---------------------------+

| id   | select_type | table | type  | possible_keys | key  | key_len | ref  | rows | Extra                     |

+------+-------------+-------+-------+---------------+------+---------+------+------+---------------------------+

|    1 | SIMPLE      | t1    | range | key1          | key1 | 5       | NULL |  101 | Using where; Using buffer |

+------+-------------+-------+-------+---------------+------+---------+------+------+---------------------------+