paired flop holding over cards

Hi.

Both opponents are unknown.

1.- I usually bet/fold this type of flops with over cards, is this OK?

2.- What do you do on the river? Why?

Thanks!

Poker Stars, $0.10/$0.25 Pot Limit Omaha Cash, 5 Players

CO: $23.59 (94.4 bb)
Hero (BTN): $81.65 (326.6 bb)
SB: $73.24 (293 bb)
BB: $23.99 (96 bb)
MP: $9.60 (38.4 bb)

Preflop: Hero is BTN with J♠ Q♣ T♥ K♠
MP calls $0.25, CO calls $0.25, Hero raises to $1.35, 2 folds, MP calls $1.10, CO calls $1.10

Flop: ($4.40) 4♥ 4♦ 5♠ (3 players)
MP checks, CO checks, Hero bets $2.31, MP calls $2.31, CO folds

Turn: ($9.02) 6♥ (2 players)
MP checks, Hero checks

River: ($9.02) K♦ (2 players)
MP bets $3, Hero ??