Preheat an air fryer to 325 degrees F (165 degrees C) according to manufacturer's instructions.
Spray kidney beans with olive oil cooking spray and toss with sea salt. Spread out in a single layer in the air fryer basket.
Air-fry until all of the kidney beans have split open and have become crisp, 25 to 30 minutes. Air-fry for 5 more minutes if they look under-toasted; they all should be varying degrees of brown.
Allow to cool and store in airtight container or sandwich bag.