CREATE TABLE `longdescs2` (

  `bug_id` int(11) NOT NULL,

  `who` int(11) NOT NULL,

  `bug_when` datetime NOT NULL,

  `thetext` mediumtext NOT NULL,

  `work_time` decimal(7,2) NOT NULL DEFAULT 0.00,

  `isprivate` tinyint(4) NOT NULL DEFAULT 0,

  `already_wrapped` tinyint(4) NOT NULL DEFAULT 0,

  `comment_id` int(11) NOT NULL AUTO_INCREMENT,

  `type` smallint(6) NOT NULL DEFAULT 0,

  `extra_data` varchar(255) DEFAULT NULL,

  PRIMARY KEY (`comment_id`),

  KEY `longdescs_bug_when_idx` (`bug_when`),

  KEY `longdescs_who_idx` (`who`,`bug_id`),

  KEY `longdescs_who_bug_when_idx` (`who`,`bug_when`),

  KEY `longdescs_bug_id_idx` (`bug_id`,`work_time`)

) ENGINE=InnoDB AUTO_INCREMENT=2818770 DEFAULT CHARSET=utf8;

INSERT INTO `longdescs2` VALUES (247765,1355,'2018-06-01 10:25:30','abcdef',1.50,0,0,2818108,0,NULL),(250659,1355,'2018-06-01 13:09:26','abcdef',2.42,0,0,2818478,0,NULL),(251629,1355,'2018-06-01 13:58:48','abcdef',1.17,0,0,2818565,0,NULL),(251658,1355,'2018-06-01 15:55:47','abcdef',0.50,0,0,2818769,0,NULL);

select * from (SELECT comment_id, 'abc' AS Who, l.who AS WhoId, l.bug_id AS BugId, SUM(l.work_time) AS Worktime FROM longdescs2 l WHERE l.bug_when >= STR_TO_DATE('01.06.2018', '%d.%m.%Y') AND l.bug_when < STR_TO_DATE('04.06.2018', '%d.%m.%Y') AND l.work_time != 0 AND l.who = 1355 GROUP BY l.who, l.bug_id) k where k.Who in ('abc');

CREATE TABLE t1 (who int);

INSERT INTO t1 VALUES (1),(1);

SELECT * FROM (SELECT 'abc' AS who FROM t1 GROUP BY t1.who) k

WHERE k.who='abc';

explain extended 

SELECT * FROM (SELECT 'abc' AS who FROM t1 GROUP BY t1.who) k

WHERE k.who='abc';

drop table t1;

 10.2

MariaDB [test]> SELECT * FROM (SELECT 'abc' AS who FROM t1 GROUP BY t1.who) k

    -> WHERE k.who='abc';

Empty set, 2 warnings (0.002 sec)

Warning (Code 1052): Column 'who' in order clause is ambiguous

Warning (Code 1292): Truncated incorrect DOUBLE value: 'abc'

MariaDB [test]> explain extended 

    -> SELECT * FROM (SELECT 'abc' AS who FROM t1 GROUP BY t1.who) k

    -> WHERE k.who='abc';

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

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

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

|    1 | PRIMARY     | <derived2> | ALL  | NULL          | NULL | NULL    | NULL |    2 |   100.00 | Using where                     |

|    2 | DERIVED     | t1         | ALL  | NULL          | NULL | NULL    | NULL |    2 |   100.00 | Using temporary; Using filesort |

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

2 rows in set, 2 warnings (0.001 sec)

Warning (Code 1052): Column 'who' in order clause is ambiguous

Note (Code 1003): /* select#1 */ select `k`.`who` AS `who` from (/* select#2 */ select 'abc' AS `who` from `test`.`t1` group by `test`.`t1`.`who`) `k` where `k`.`who` = 'abc'