Coleraine Library and PRONI both have the following on 1 microfilm reel:
Killowen Parish Church
vol 1: bapt1824-1841; marr 1824-1831; burials 1825-1830
vol 2: bapt 1824-1843; marr 1824-1843
vol 3: bapt 1843-1857; confirmations 1844, 1849, 1855
vol 4: marr 1843-1845
vol 5: burials 1843-1881, 1893-1901
vol 6: bapt 1857-1869
Not 100% sure but think some of it might be difficult to read
Anything more recent would be in local custody