MySQL BETWEEN两个日期时间不使用INDEX

explain
SELECT COUNT(*) AS Count, CreatedBy
FROM `Notes`
INNER JOIN Users ON UserID = CreatedBy
INNER JOIN UserRoles ON URoleID = RoleID AND RoleID = 1
WHERE NoteVisible = 1 AND NoteText NOT LIKE '%SOME KEYWORD%' 
      AND Created BETWEEN '2014-02-24 00:00:00' AND '2014-02-24 23:59:59' 
GROUP BY CreatedBy
explain
SELECT COUNT(*) AS Count, CreatedBy
FRO