desc code_name;
+------------+------------------+------+-----+---------+-------+
| Field      | Type             | Null | Key | Default | Extra |
+------------+------------------+------+-----+---------+-------+
| start  | int(11) unsigned | YES  | MUL | NULL    |       |
| end    | int(11) unsigned | YES  | MUL | NULL    |       |
| code       | char(2)          | YES  |     | NULL    |       |
+------------+------------------+------+-----+---------+-------+
8 rows in set (0.00 sec)

mysql> explain select code from code_name where 3340638336>=start and 3340638336<=end;
+----+-------------+--------+------+-------------------+------+---------+------+---------+-------------+
| id | select_type | table  | type | possible_keys     | key  | key_len | ref  | rows    | Extra       |
+----+-------------+--------+------+-------------------+------+---------+------+---------+-------------+
|  1 | SIMPLE      | code_name | ALL  | start,end | NULL | NULL    | NULL | 3235099 | Using where |
+----+-------------+--------+------+-------------------+------+---------+------+---------+-------------+
1 row in set (0.00 sec)