mysql> SHOW INDEX FROM blogs;
+-------+------------+--------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
| Table | Non_unique | Key_name                             | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | Visible | Expression |
+-------+------------+--------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
| blogs |          0 | PRIMARY                              |            1 | id          | A         |           0 |     NULL |   NULL |      | BTREE      |         |               | YES     | NULL       |
| blogs |          1 | index_blogs_on_user_id               |            1 | user_id     | A         |           0 |     NULL |   NULL |      | BTREE      |         |               | YES     | NULL       |
| blogs |          1 | index_blogs_on_publish_at            |            1 | publish_at  | A         |          15 |     NULL |   NULL | YES  | BTREE      |         |               | YES     | NULL       |
| blogs |          1 | index_blogs_on_status_and_publish_at |            1 | status      | A         |           2 |     NULL |   NULL | YES  | BTREE      |         |               | YES     | NULL       |
| blogs |          1 | index_blogs_on_status_and_publish_at |            2 | publish_at  | A         |          15 |     NULL |   NULL | YES  | BTREE      |         |               | YES     | NULL       |
| blogs |          1 | index_blogs_on_publish_at_and_status |            1 | publish_at  | A         |          15 |     NULL |   NULL | YES  | BTREE      |         |               | YES     | NULL       |
| blogs |          1 | index_blogs_on_publish_at_and_status |            2 | status      | A         |          15 |     NULL |   NULL | YES  | BTREE      |         |               | YES     | NULL       |
+-------+------------+--------------------------------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+---------+------------+
7 rows in set (0.01 sec)

SELECT * 
FROM blogs
WHERE status = 1
ORDER BY publish_at DESC;

mysql> EXPLAIN SELECT * FROM blogs WHERE status = 1 ORDER BY publish_at DESC;

+----+-------------+-------+------------+------+--------------------------------------+--------------------------------------+---------+-------+------+----------+---------------------+
| id | select_type | table | partitions | type | possible_keys                        | key                                  | key_len | ref   | rows | filtered | Extra               |
+----+-------------+-------+------------+------+--------------------------------------+--------------------------------------+---------+-------+------+----------+---------------------+
|  1 | SIMPLE      | blogs | NULL       | ref  | index_blogs_on_status_and_publish_at | index_blogs_on_status_and_publish_at | 5       | const |   15 |   100.00 | Backward index scan |
+----+-------------+-------+------------+------+--------------------------------------+--------------------------------------+---------+-------+------+----------+---------------------+
1 row in set, 2 warnings (0.00 sec)