Pour water into Instant Pot®. Insert trivet. Place steamer basket onto trivet.
Prepare asparagus by finding the natural snap point on the stalks and discarding the woody ends.
Spread the asparagus on the bottom of the steamer basket. Sprinkle with 1/2 tsp salt. Add the shrimp. Squeeze lemon into the Instant Pot®, then sprinkle shrimp with remaining 1/2 tsp salt. Place pats of butter on shrimp. Lock lid.
Press the Manual button and adjust time to 1 minute.
When the timer beeps, quick-release the pressure until the float valve drops and then unlock lid.
Transfer shrimp and asparagus to a platter and serve.