Applying the spraypaint will help to prevent corrosion. You have to prepare the object tough. Moisture and oxygen can still get to the metal. It´s important to clean the object and not touch it before the paint is applied. We had a demonstration on that one. We cleaned a piece of steel touched it with hands that were a little sweaty and applied clear spray paint. After a few weeks we could see the rusty fingerprints.
If you carry the object in a pocket the paint will likely be damaged.