Spotify tried to mess me up. I found a song that’s three minutes exactly (in the description of the round on Music League, it’s referred to as ‘a song three minutes long or less’).
Added it to a playlist, and it rang up as 3:01. Went back to the song’s page to check: 3:00. Deleted it, added it again, 3:01.
Anyway, I won’t be trying to min-max the length rules.