Heidar Helguson opened the scoring in the first half before going down under the flailing arm of Darius Henderson, who was shown a red card for his troubles.
That left Rudy Gestede to rattle home a second-half double and ensure a comfortable win for the Bluebirds, but Mackay is simply refocusing on the next game.
He said: "I was pleased with how we played up to the sending-off against a team who are really on form. We had to go toe-to-toe from the first minute and we did that.
"We got the goal and then after the sending-off it can be difficult to play against 10 men but we were absolutely on the money.
"We now have a game against Charlton, against who we gave our poorest performance of the season at The Valley, and we know we will have a tough game against them here.
"We had a record attendance here today and I would imagine there is not a ticket to be had for Tuesday, and we will go into the next game in the same vein as today and the same vein as last Tuesday against Barnsley."
On the contribution of Benin star Gestede, Mackay added: "I loved his attitude when he arrived here. He wanted to throw himself into everything.
"There are rough edges that have been smoothed out, and are being smoothed out, but there are times when he looks unplayable."