explain
select * from (
select 1 as foo
from sakila.actor as actor_1,
sakila.actor as actor_2
) as x;
+----+-------------+------------+-------+---------------+---------+---------+------+-------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+------------+-------+---------------+---------+---------+------+-------+-------------+
| 1 | PRIMARY | <derived2> | ALL | NULL | NULL | NULL | NULL | 40000 | |
| 2 | DERIVED | actor_1 | index | NULL | PRIMARY | 2 | NULL | 200 | Using index |
| 2 | DERIVED | actor_2 | index | NULL | PRIMARY | 2 | NULL | 200 | Using index |
+----+-------------+------------+-------+---------------+---------+---------+------+-------+-------------+
|