id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE	m	index_merge	idx-match-team1_id,idx-match-team2_id,idx-match-start_dt	idx-match-team1_id,idx-match-team2_id	5,5	NULL	3	Using union(idx-match-team1_id,idx-match-team2_id); Using where; Using filesort