You can do this easily by 2 methods
1.) select date_add(datetime_field, interval 330 minute) from table_name
OR
2.) Select DATE_ADD(DATE_ADD(datetime_field ,INTERVAL 5 HOUR),INTERVAL 30 MINUTE) as datetime_field from table_name
However, as stated in some articles on the internet it's best if you correct the problem from the source and update the timezone in your DBMS like