Hello Maartinss,
Preflop: Well, if you expect the CO to raise with very wide range and most likely even is able to rather call than 4bet then your implied odds should be fine. ~15:1 so for a 3bet pot should be enough.
As played
Postflop: Wouldn't change much. The K still improves some of their range. Don't be result oriented. Of course there would be possible to bet it but I'd rather take the passive line, if we are ahead then we are ahead with our 55 anyways. Doubt that we are making better hands to fold.
Best regards.