In the Musixmatch API documentation it is said
Get an album from our database: name, release_date, release_type, cover art.
In the JSON response example there is also "album_coverart_100x100", but when I'm making an API call, in the response there is no image availible.
You can get an album art field as the response of
album.get, but not fromtrack.search. So if you're trying to show the album art for a result that the user has searched for, you might want to make another api call toalbum.getand get the value of the keyalbum_coverart_100x100for the url of the album art.