Query optimize on large database

[Pavel Volkov]

Hey guys! I'got table with 300kk rows and ~40 GB size

It got simple structure like [owner_id, Artist, Title] (user's songs list)

My task is simple - need to select the number of matches user's Artist+Title pair (songs) with specified @user_id and display it like [user_id:number_of_matches with specified @user_id]

Got query like that:

SELECT d2.owner_id, COUNT(*) AS kolvo
FROM data d1
JOIN data d2 USING(Artist,Title)
WHERE d1.owner_id = @user_id
GROUP BY d1.owner_id


Got indexes [Artist,Title] and [owner_id]


But the bigger table becomes the more time it takes to execute query...
At first it was pretty fast but now it takes around 1 minute to finish.

Any ideas how to optimize my task? Thanks a lot!