Place the green beans in a mixing bowl and drizzle with olive oil. Toss well until all beans are lightly coated.
Sprinkle the salt evenly over the beans and toss again to distribute the seasoning uniformly.
Preheat the air fryer to 200°C (390°F) for about 3 minutes to ensure even roasting.
Arrange the green beans in the air fryer basket in a single layer, avoiding overcrowding for optimal crispness.
Cook the beans for 8-10 minutes, shaking the basket halfway through to promote even browning and crisp edges.
Check the beans at 8 minutes; they should be tender with golden tips and a crispy exterior. If needed, roast for an additional 2 minutes.
Transfer the roasted green beans to a serving bowl and squeeze fresh lemon juice over them for a bright, tangy finish.
Toss gently to combine, taste, and adjust salt if necessary. Serve immediately to enjoy the crispy, smoky green beans.