I've added an index on the auth field. Query duration went from 90 seconds to 0.01 seconds.
Code:
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 |
+------+-------------+------------------+------+---------------+------+---------+-------+------+------------------------------------+