A good way to keep food warm without having it dry out is by turning your oven on low heat, and then place a shallow pan with water on the lowest shelf in the oven, then place the pan with the food you want to keep warm in the shallow pan with the water but make sure to cover the pan that has the food in it.
Make sure you check the food in the oven frequently to be sure the pan still has water in it and prevent the food from drying out and burning.