I watched a TV-program where they made a mixture of old breads. It has no water in it so it is mainly carbohydrates. They used it to fry up such as chicken and fish.
How long can you store such a mixture?
It sounds like you're talking about bread crumbs--you use these to bread the outside of anything you'd want to fry up (i.e. chicken breasts).
If you stored this in a sealed container and kept this in a cool place, I would say a few months, at least. It's possible that something like this would last for over a year or longer without going moldy.
After a few months, I would just give it a close visual inspection and taste a small amount. Are the bread crumbs moldy? Are they stale? Do they still have any flavor (if there was any to begin with)? If it passes all these tests, I'd use it. Even if it's stale, I may still try to make a small batch of food with it because baking and frying heats water out of foods anyways.
Side note: My parents have some ground spices in their kitchen from over a decade ago. The spices haven't gone moldy and I don't get sick eating food with these spices in it. However, the difference in flavor between these spices and new ones are like day and night. When I cook there, I don't bother using their spices, but I won't complain if they use it for food served to me.