Crispy cold fried chicken
There’s a food processing trick, where producers use dextrin to keep the coating crisp for hours. You simply replace some of the flour (around 20%) in your recipe with dextrin and you’re good to go.

As the other answer mentions, multiple layers also helps creating a thick barrier to slow down moisture seeping into the coating. You can use dextrin in both layers.

Once you’ve adapted your recipe to use dextrin, frying followed by rapid cooling should give you a good result.