Query Locked Objects from vlocked_object
 
SELECT SUBSTR(b.owner, 1, 8) owner, b.object_type, SUBSTR(b.object_name, 1, 18)object_name
 , DECODE(a.locked_mode
        , 0, 'None'
        , 1, 'Null'
        , 2, 'Row-S'
        , 3, 'Row-X'
        , 4, 'Share'
        , 5, 'S/Row-X'
        , 6, 'Exclusive')  locked_mode
 , a.session_id,a.oracle_username, a.os_user_name, TO_CHAR(c.logon_time,'YYYY/MM/DD HH24:MI:SS') logon_time, c.PROGRAM,c.saddr
FROM
  vlocked_object a
 , dba_objects b
 , vsession c
WHERE
 a.object_id  = b.object_id  AND a.session_id = c.sid
ORDER BY  b.object_name, b.owner, b.object_type