Striker Benjamin York broke the deadlock to score his first goal of the season with a spectacular strike on the stroke of halftime to put the Phobians ahead.
Karela levelled seven minutes to full-time when substitute Emmanuel Owusu Boakye connected a cross from Augustine Randolph.
A win for Hearts of Oak would have prolonged Asante Kotoko's fight to win the Ghana Premier League title.
Kotoko now require just one point from the remaining three matches to be crowned champions of the 2021-22 season.
Watch match highlights below