+----+-------------+-------+------+---------------+------+---------+------+---------+-------------+
| id | select_type | table | type | possible_keys | key  | key_len | ref  | rows    | Extra       |
+----+-------------+-------+------+---------------+------+---------+------+---------+-------------+
|  1 | SIMPLE      | smtp  | ALL  | dttm          | NULL | NULL    | NULL | 1901530 | Using where |
+----+-------------+-------+------+---------------+------+---------+------+---------+-------------+