MySQL EXPLAIN Explained

id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	filtered	Extra
1	PRIMARY	film	NULL	ALL	NULL	NULL	NULL	NULL	1000	100.00	NULL
2	DEPENDENT SUBQUERY	film_category	NULL	ref	film_category_pk film_category_category_id film_category_film_id	film_category_pk	2	sakila.film.film_id	1	100.00	Using index
2	DEPENDENT SUBQUERY	category	NULL	eq_ref	PRIMARY	PRIMARY	1	sakila.film_category.category_id	1	100.00	NULL