Do you know what denomination your King family were ?
Not many parishes have records back as far as 1809, so you would usually need to know a more detailed location to start a check to see if there are records available - i.e. the name of the parish or town..
Some Church of Ireland records (no RC records at the moment) for Co. Carlow are available on www.irishgenealogy.ie
including a few with the King surname..including several different families where the father's name is John, but no close matches for Mary's baptism..