Kalvin Phillips, Jack Clarke and Jack Taylor scored for the hosts on Sunday.
McKenna later said: "I thought it was a really good one. Lots of good individual performances. Could have scored more and gone to be in the next round. It was a really good match from our perspective and a really enjoyable watch, even from the sidelines. We gave nothing away and left with a clean sheet."
On Phillips' goal, he continued: "Nice for him to get his first goal. They both did a really good job in there and connected well with their team-mates."
On Clarke's first goal, McKenna also said: "It's an important one and it's nice for him to get it. His relationship with Townsend looked really good down the left.
"It's a brilliant competition and we want to go as far as we can and give the supporters some memories. We also want the games this year, we've got a big squad we want to give them some minutes.
On Ben Godfrey's debut, he added: "It was good to get him in, it was an opportunity to do so. He hasn't had much game time but he did well and showed his quality on the ball"