Wash the asparagus spears and snap off the tough woody ends. Pat them completely dry with paper towels - this is important for getting the coating to stick properly.
Set up a three-station breading line. Place the all-purpose flour in a shallow dish. In a second shallow dish, whisk together the eggs and water. In a third shallow dish, combine the panko breadcrumbs, grated parmesan cheese, garlic powder, salt, and black pepper.
Working with a few spears at a time, dredge each asparagus spear in flour and shake off the excess. Dip into the egg mixture, letting the excess drip off. Finally, roll in the panko mixture, pressing gently so the coating adheres well.
Preheat the air fryer to 400 degrees F for 2 minutes. Arrange the breaded asparagus in a single layer in the basket, leaving space between each spear. Lightly spray the tops with nonstick cooking spray. Work in batches as needed.
Air fry at 400 degrees F for 6 to 8 minutes, flipping the spears halfway through and giving another light spray of cooking spray. They are done when the coating is deep golden and crunchy.
Transfer to a serving plate and repeat with any remaining batches. Serve immediately with lemon wedges for squeezing. These are best enjoyed right away while the panko crust is at its crispiest.