It is rare they measure bags in my experience but if your carry on is noticeably larger than normal it may get pulled for a check. If only half an inch over (and the other dimensions are ok, especially depth) then it will likely be fine. Key here is it fits length ways in the overhead storage, margins are tight in this but I reckon there is half an inch play especially if you have included the handle in the calculation and if this can squash down a bit.
For example BA (which also fly A320) allow 22" or 56cm of height so it should fit.