In case you have your own slow SQL query, you can optimize it automatically here.
For the query above, the following recommendations will be helpful as part of the SQL tuning process.
You'll find 3 sections below:
ALTER TABLE `decklist` ADD INDEX `decklist_idx_card_name_deck_id_quantity` (`card_name`,`deck_id`,`quantity`);
SELECT
t.deck_id
FROM
decklist t
INNER JOIN
decklist l
ON l.deck_id = t.deck_id
WHERE
(
t.card_name = 'madeupcard'
AND t.quantity >= 1
)
AND (
l.card_name = 'cardofblahblah'
AND l.quantity >= 3
)