MariaDB [teeworlds]> EXPLAIN SELECT Name, a.ID, Time, DENSE_RANK() OVER (ORDER BY Time) rank FROM record_teamrace AS a JOIN (SELECT ID FROM record_teamrace WHERE Map="Stronghold" GROUP BY ID ORDER BY Time LIMIT 5) AS b on a.ID=b.ID;
+------+-------------+-----------------+------+----------------+---------+---------+-------+------+-----------------------------------------------------------+
| id   | select_type | table           | type | possible_keys  | key     | key_len | ref   | rows | Extra                                                     |
+------+-------------+-----------------+------+----------------+---------+---------+-------+------+-----------------------------------------------------------+
|    1 | PRIMARY     | <derived2>      | ALL  | NULL           | NULL    | NULL    | NULL  |    5 | Using temporary                                           |
|    1 | PRIMARY     | a               | ref  | ID             | ID      | 18      | b.ID  |    1 | Using index                                               |
|    2 | DERIVED     | record_teamrace | ref  | PRIMARY,Map,ID | PRIMARY | 514     | const |  728 | Using where; Using index; Using temporary; Using filesort |
+------+-------------+-----------------+------+----------------+---------+---------+-------+------+-----------------------------------------------------------+
3 rows in set (0.001 sec)

MariaDB [teeworlds]> EXPLAIN SELECT Name, Time, Rank, TeamSize FROM (
    ->     SELECT TeamSize, Rank, ID
    ->         FROM (SELECT RANK() OVER w AS Rank, ID, COUNT(*) AS Teamsize
    ->                 FROM record_teamrace
    ->                 WHERE Map="Stronghold"
    ->                 GROUP BY Id
    ->                 WINDOW w AS (ORDER BY Time)
    ->         ) as l1
    ->         ORDER BY Rank ASC
    ->         LIMIT 5
    ->     ) as l2
    -> INNER JOIN record_teamrace as r ON l2.ID = r.ID
    -> ORDER BY Rank ASC, r.ID, Name ASC;
+------+-------------+-----------------+------+---------------+---------+---------+-------+------+-----------------------------------------------------------+
| id   | select_type | table           | type | possible_keys | key     | key_len | ref   | rows | Extra                                                     |
+------+-------------+-----------------+------+---------------+---------+---------+-------+------+-----------------------------------------------------------+
|    1 | PRIMARY     | <derived2>      | ALL  | NULL          | NULL    | NULL    | NULL  |    5 | Using temporary; Using filesort                           |
|    1 | PRIMARY     | r               | ref  | ID            | ID      | 18      | l2.ID |    1 | Using index                                               |
|    2 | DERIVED     | <derived3>      | ALL  | NULL          | NULL    | NULL    | NULL  |  728 | Using filesort                                            |
|    3 | DERIVED     | record_teamrace | ref  | PRIMARY,Map   | PRIMARY | 514     | const |  728 | Using where; Using index; Using temporary; Using filesort |
+------+-------------+-----------------+------+---------------+---------+---------+-------+------+-----------------------------------------------------------+
4 rows in set (0.001 sec)