The RC records for Holycross parish start in 1835.
I also looked at the 1834 Tithe listings for the parish and did not see any Keogh records.
The 1850 Griffiths Valuation head of household listing for Holycross civil parish shows two Keogh records: a John Keogh in Whitefort townland and a Patrick Keogh in Grange townland. https://www.failteromhat.com/griffiths/tipperary/holycross.htm
I located a Thomas Keough in Whitefort townland in the 1901 census