The week after Passover, the Jews maintain a custom of baking challah either in the shape of a key or with a key baked into the challah. The principal reason is that when the Jewish nation went out of Egypt through the desert, it lacked food. The Almighty sent the mon, the food from heaven, to the Jewish nation.
This key-shaped challah represents the key to our livelihood, serving as a reminder that our success is in the Almighty’s hands. The prayer with this custom requests that the Almighty opens the gates of livelihood to all of us.