mysql> explain SELECT * FROM wp_comments /*!40000 IGNORE INDEX (comment_approved) */ WHERE comment_post_ID = '1' AND comment_approved = '1' ORDER BY comment_date DESC; +----+-------------+-------------+------+------------------------+--------+---------+-------------+------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------------+------+------------------------+--------+---------+-------------+------+-------------+ | 1 | SIMPLE | wp_comments | ref | comment_post_ID,comidx | comidx | 5 | const,const | 9 | Using where | +----+-------------+-------------+------+------------------------+--------+---------+-------------+------+-------------+ 1 row in set (0.00 sec)