$0.02/$0.05

SB: $5 (100 bb)
BB: $10.05 (201 bb)
MP: $5.96 (119.2 bb)
CO: $4.54 (90.8 bb)
Hero (BTN): $5.26 (105.2 bb)

Preflop: Hero is BTN with Ac 3c
2 folds, Hero raises to $0.12, SB folds, BB raises to $0.49, Hero calls $0.37

Flop: ($1) Ks 7c 9c (2 players)
BB bets $0.72, Hero raises to $2.10, BB raises to $5.96, Hero calls $2.67 and is all-in

Villain is unkown.

Can I call preflop? Should I just call on flop? What's the best play here?