mysql> explain SELECT user.login FROM user LEFT JOIN alias ON alias.target_id=user.id LEFT JOIN virtual ON alias.domain=virtual.id WHERE alias.login='sdfdsf' AND virtual.name='dsfdsf.org';
+----+-------------+---------+------+------------------+-----------+---------+--------------+-------+--------------------------+
| id | select_type | table   | type | possible_keys    | key       | key_len | ref          | rows  | Extra                    |
+----+-------------+---------+------+------------------+-----------+---------+--------------+-------+--------------------------+
|  1 | SIMPLE      | virtual | ref  | PRIMARY,name     | name      | 257     | const        |     1 | Using where; Using index |
|  1 | SIMPLE      | user    | ALL  | PRIMARY          | NULL      | NULL    | NULL         | 23060 |                          |
|  1 | SIMPLE      | alias   | ref  | domain,target_id | target_id | 4       | sys_.user.id |     1 | Using where              |
+----+-------------+---------+------+------------------+-----------+---------+--------------+-------+--------------------------+
3 rows in set (0.01 sec)