Snap the asparagus ends off. You can just grab the asparagus near the base and snap, they should naturally snap where the asparagus goes from woody to tender. Discard the stems and place the spears on a baking sheet.
Drizzle with olive oil and season with salt and pepper. Toss to coat evenly.
Preheat your air fryer to 400°F. Arrange half of the asparagus in a single layer in the air fryer basket.
Air fry for 4 to 5 minutes. If your asparagus is smaller, you can take them out a few minutes earlier so they don't get too soft. Repeat with the second half of asparagus. Serve the asparagus with fresh lemon juice, and optionally parmesan cheese and red pepper flakes sprinkled on top. Enjoy!