Tune SQL statement (v 10g)

I'm trying to find if there might be a more efficient way of doing this SQL statement.  If I'm following it right it is just making sure that there isn't more than one dest_store in pre_case_pack table for the matching rows in pre_case (where pick_nbr is null).

SELECT bl_nbr,
         case_nbr,
         case_pack_type,
         DECODE (pre_case.store, :1, NVL (needs_ticketing, 'N'), 'N'),
         DECODE (pre_case.store, :2, , pre_case.store)
    FROM pre_case
   WHERE     pick_nbr IS NOT NULL
         AND EXISTS
                (SELECT *
                   FROM pre_Case_pack
                  WHERE case_nbr = pre_case.case_nbr AND dest_store = :4)