Hello,

Villain is unknown (10 hands only). His donk bet and reraise could represent a set or an overpair I think; but it could be a lot of others hands like a 9 or a flushdraw.

So is the all in ok, or is it to optimistic ?

No-Limit Hold'em, $0.05 BB (6 handed) - Hold'em Manager Converter Tool from FlopTurnRiver.com
MP ($2.02)
CO ($2.44)
Button ($10.08)
SB ($4.85)
BB ($5.47)
Hero (UTG) ($5)
Preflop: Hero is UTG with A, K
Hero bets $0.20, 3 folds, SB calls $0.18, 1 fold
Flop: ($0.45) 2, 4, 9 (2 players)
SB bets $0.20, Hero raises $0.60, SB raises $1.25, Hero raises $4.20 (All-In)