between operator mysql

Use beetween operator in mysql correctly, that use column's indexes .
Example of great correctly query:

SELECT * FROM news

  WHERE created_at BETWEEN STR_TO_DATE('2008-08-14 00:00:00', '%Y-%m-%d %H:%i:%s')

  AND STR_TO_DATE('2008-08-23 23:59:59', '%Y-%m-%d %H:%i:%s');