I research the Irish Family History Foundation's database. It contains 12,000,000 surviving rcds for abt 65% of Irish counties. Rcds are increasingly sparse B4 1840, rare B4 1800.
Note 1 - Without a KNOWN county, the chance of an ancestor's rcds NOT being in this database is AT LEAST 35%.
Note 2 - Only 1/2 of Co. Cork's rcds are in this database.
Note 3 - The RC church kept control over most parish rcds from Tipperary (north). These are ONLY available thru the Tipperary Family History Research center at a substantial fee (regardless of outcome).
For Tho(mas) Kehoe (+variants) B 1842 +/- 2 yrs somewhere in Ireland with the father's forename unknown, I found 27 rcds - too many to easily summarize here.
For Cat(herine) Loy B 1844 +/- 2 yrs ditto, I found 8 rcds: 2-1842 Tyrone, 1843 Armagh, 1844 Louth, 1845 Meath, and 3-1846 Armagh. Father's respective forenames were James, Patrick, Thomas, Thomas, James, Patrick, James, and John.
The above MAY contain rcds for your ancestors. You will need an exact DOB/DOM, parent(s) name(s), and/or placename(s) to pick which, if any, are the right ones.
Note - none of John's 27 rcds are in counties which match the set for Catherine. This infers they met and married in America. Church rcds are the most likely place to find their parents' names and placenames in Ireland.
Google the Foundation's name to lead you to this database. Register, opt to be notified as rcds are added and browse. Pls post your search results to my genforum msg.