The parish record - “Ireland Select Catholic Marriage Registers 1778- 1942 “ shows his parents as Thomas Kelley and Mary Kelley of Mountrath - as is William with surname ‘Kelley’.
Other parents names show the mother’s maiden name but Mary is shown as Kelley/Kelly.
This marriage - February 4th 1857 has been transcribed elsewhere as Thomas ‘Pullts’ and Mary Hurly but it could read Kelly.
Is this the one you mean?
https://registers.nli.ie/registers/vtls000634519?locale=en#page/107/mode/1up