mysql> explain select confession_id from Confessions.scores where score > 0.5 order by rand() limit 1;
+----+-------------+--------+------+---------------+------+---------+------+------+----------------------------------------------+
| id | select_type | table  | type | possible_keys | key  | key_len | ref  | rows | Extra                                        |
+----+-------------+--------+------+---------------+------+---------+------+------+----------------------------------------------+
|  1 | SIMPLE      | scores | ALL  | NULL          | NULL | NULL    | NULL |   64 | Using where; Using temporary; Using filesort |
+----+-------------+--------+------+---------------+------+---------+------+------+----------------------------------------------+