id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	match	index_merge	idx-match-team1_id,idx-match-team2_id	idx-match-team1_id,idx-match-team2_id	5,5	NULL	17	Using union(idx-match-team1_id,idx-match-team2_id); Using where; Using filesort
1	SIMPLE	tournament	eq_ref	PRIMARY	PRIMARY	4	bsr.match.tournament_id	1	Using where