Penalty for leaving rant

Getting into a match of dominion against 4 cents and my team has one bot. 3v4, so what I'm not complaining. About halfway through the match my two other team mates go completely afk, making me the only participant on my team. I'm supposed to stay in the shit show of a match and just take my licks? Now I'm sitting here locked out of matchmaking for quiting a terrible excuse of a match early. I guess it beats getting my assholr stretched by 4 manlets late for their toga party.