EXPLAIN SELECT * FROM table_name WHERE id IN (1,2,3,4,5,6,7,8,9) AND pole_2 IS NULL ORDER BY id DESC;

           id: 1
  select_type: SIMPLE
        table: table_name
         type: ref
possible_keys: PRIMARY,pole_2
          key: pole_2
      key_len: 5
          ref: const
         rows: 9
        Extra: Using where

+------------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+
| Table      | Non_unique | Key_name  | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | 
+------------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+
| table_name |          0 | PRIMARY   |            1 | id          | A         |  1856244572 |     NULL | NULL   |      | BTREE      |
| table_name |          1 | pole_2    |            1 | pole_2      | A         |   309374095 |     NULL | NULL   | YES  | BTREE      |
+------------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+