No auth index +------+-------------+------------------+------+---------------+------+---------+------+---------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +------+-------------+------------------+------+---------------+------+---------+------+---------+-------------+ | 1 | PRIMARY | player_analytics | ALL | NULL | NULL | NULL | NULL | 5986079 | Using where | | 2 | SUBQUERY | player_analytics | ALL | NULL | NULL | NULL | NULL | 5986079 | Using where | +------+-------------+------------------+------+---------------+------+---------+------+---------+-------------+ With auth index +------+-------------+------------------+------+---------------+------+---------+-------+------+------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +------+-------------+------------------+------+---------------+------+---------+-------+------+------------------------------------+ | 1 | PRIMARY | player_analytics | ref | auth | auth | 99 | const | 64 | Using index condition | | 2 | SUBQUERY | player_analytics | ref | auth | auth | 99 | const | 64 | Using index condition; Using where | +------+-------------+------------------+------+---------------+------+---------+-------+------+------------------------------------+