Pray is always a verb. To pray is (1) to utter a prayer to a god or another higher power, and (2) to make a fervent request.
Prey is (1) a noun referring to one that is hunted or attacked, and (2) a verb meaning to hunt, catch, or eat as prey.
Others compare drought to a python, which slowly and inexorably squeezes its prey to death. [New York Times]
They, evidently, agreed that I ought not to pray in the church basement nor to pray on the church grounds. [Marshall Independent]
An unemployed man from Utah is advertising himself as the prey for hunting enthusiasts for $10,000. [Independent]
Two weeks away from the federal government defaulting on its debts — how, pray tell, has this come to pass? [CNN]