Not in ,Subquery

mysql> explain select servername,serverarea,faction, charactername from all_customers where  (servername,serverarea,faction,charactername) in (select servername,serverarea,faction,charactername from active_customers);
+----+--------------------+------------------+----------------+----------------+----------------+---------+---------------------+--------+--------------------------+
| id | select_type        | table            | type           | possible_keys  | key            | key_len | ref                 | rows   | Extra                    |
+----+--------------------+------------------+----------------+----------------+----------------+---------+---------------------+--------+--------------------------+
|  1 | PRIMARY            | all_customers    | index          | NULL           | index_all      |      87 | NULL                | 413891 | Using where; Using index |
|  2 | DEPENDENT SUBQUERY | active_customers | index_subquery | idx_server_all | idx_server_all |      87 | func,func,func,func |      1 | Using index; Using where |
+----+--------------------+------------------+----------------+----------------+----------------+---------+---------------------+--------+--------------------------+
2 rows in set (0.00 sec)

mysql> explain select servername,serverarea,faction, charactername from all_customers where  (servername,serverarea,faction,charactername) not in (select servername,serverarea,faction,charactername from active_customers);
+----+--------------------+------------------+-------+----------------+----------------+---------+------+--------+--------------------------+
| id | select_type        | table            | type  | possible_keys  | key            | key_len | ref  | rows   | Extra                    |
+----+--------------------+------------------+-------+----------------+----------------+---------+------+--------+--------------------------+
|  1 | PRIMARY            | all_customers    | index | NULL           | index_all      |      87 | NULL | 413891 | Using where; Using index |
|  2 | DEPENDENT SUBQUERY | active_customers | ref   | idx_server_all | idx_server_all |      40 | func |    542 | Using where; Using index |
+----+--------------------+------------------+-------+----------------+----------------+---------+------+--------+--------------------------+
2 rows in set (0.00 sec)