McCarthy singled out goalscorers Aaron Cresswell and Frank Nouble for praise on a good night for Town at Portman Road.
"We're in a far better position than a lot of clubs, but we're not mathematically safe yet," McCarthy said.
"We've got three to play, so we've got to keep our focus and make sure we do our job properly.
"Aaron's goal has to be a contender for goal of the season and Frank finished his goals really well.
"Even for his first one, he had to come back onto his right foot and didn't take a slash at it.
"He was calm and his second goal was a great finish. He ran their back four all over the place and I thought he was excellent.
"Goals change games but we defended really well. When it got tough we stayed tough and didn't give anything away."