NL5 Zoom AKs

Poker Stars, $0.02/$0.05 No Limit Hold'em Cash, 9 Players

BTN: $2.98 (59.6 bb)
SB: $4.79 (95.8 bb)
BB: $5.32 (106.4 bb)
UTG+1: $5.01 (100.2 bb)
Hero (UTG+2): $5 (100 bb)
MP1: $2.33 (46.6 bb)
MP2: $5.13 (102.6 bb)
MP3: $8.95 (179 bb)
CO: $2.28 (45.6 bb)

Preflop: Hero is UTG+2 with A K
UTG+1 raises to $0.15, Hero raises to $0.45, 2 folds, MP3 calls $0.45, CO folds, BTN calls $0.45, 2 folds, UTG+1 calls $0.30

Flop: ($1.87) 3 7 3 (4 players)
UTG+1 checks, Hero checks, MP3 checks, BTN checks

Turn: ($1.87) 5 (4 players)
UTG+1 checks, Hero checks, MP3 checks, BTN checks

River: ($1.87) 5 (4 players)
UTG+1 checks, Hero checks, MP3 checks, BTN checks

Should I have made a CB here and if so what size should I make it. I only have a few hands on the villains at this point.