+----+-------------+------------------+--------+----------------+---------+---------+------------------------+------+--------------------------------------+
| id | select_type | table            | type   | possible_keys  | key     | key_len | ref                    | rows | Extra                                |
+----+-------------+------------------+--------+----------------+---------+---------+------------------------+------+--------------------------------------+
|  1 | SIMPLE      | submission       | index  | PRIMARY        | PRIMARY | 4       | NULL                   |    2 |                                      |
|  1 | SIMPLE      | submission_tag_1 | eq_ref | PRIMARY,tag_id | PRIMARY | 8       | fa.submission.id,const |    1 | Using index                          |
|  1 | SIMPLE      | submission_tag_2 | eq_ref | PRIMARY,tag_id | PRIMARY | 8       | fa.submission.id,const |    1 | Using where; Using index; Not exists |
+----+-------------+------------------+--------+----------------+---------+---------+------------------------+------+--------------------------------------+
3 rows in set (0.00 sec)