As no one has answered this I will give it a try. The problem is I don't know the name of the place. Here goes...
DD and I flew to Orlando with Canjet Airlines in May. We had a 6:10 am flight. DH dropped us off at the airport at 3:40am. We checked in with the airline and proceeded to Customs and Immigration. We had to wait for them to open the waiting area. Once that was open we had to wait for Customs and Immigration to open. It opened at 4:30am. Once we were through C & I we proceeded to security. After going through security right when you enter the boarding areas there is a cafeteria style restaurant. Pick up a tray go through a line. They had muffins, croissants, bagels, pre-made sandwiches, coffee, juice, water, tea. They may have had some cereal but I'm not sure. Pay at the end of the line and find a seat in the seating area. It was the only food place open when we got through security. We asked at Fridays American Bar and they didn't open until 6:30am. We also checked at Toast of Toronto which is further along, closer to the boarding areas but it wasn't open yet either. I hope this helps.