KK on low board

[kekedarius]

PokerStars No-Limit Hold'em, $0.50 BB (6 handed) Hand History Converter Tool (http://poker-tools.flopturnriver.com/Hand-Converter.php) from FlopTurnRiver.com (http://www.flopturnriver.com) (Format: 2+2 Forums)

Hero ($70.85)
CO ($46.75)
Button ($38.15)
SB ($56.50)
BB ($14.45)
UTG ($45.10)

Preflop: Hero is MP with K/images/graemlins/diamond.gif, K/images/graemlins/spade.gif.
UTG calls $0.50, <font color="#CC3333">Hero raises to $2.5</font>, <font color="#666666">2 folds</font>, SB calls $2.25, <font color="#666666">1 fold</font>, UTG folds.

Flop: ($6) 3/images/graemlins/heart.gif, 6/images/graemlins/club.gif, 7/images/graemlins/diamond.gif <font color="#0000FF">(2 players)</font>
SB checks, <font color="#CC3333">Hero bets $4.5</font>, <font color="#CC3333">SB raises to $10</font>, Hero calls $5.50.

Turn: ($26) 3/images/graemlins/spade.gif <font color="#0000FF">(2 players)</font>
<font color="#CC3333">SB bets $12</font>, Hero calls $12.

River: ($50) T/images/graemlins/club.gif <font color="#0000FF">(2 players)</font>
SB checks, Hero checks.

Final Pot: $50

Villain is 18/7/0. His passiveness makes me worry here; should I be betting on any street?