You won't be able to use Henry's law at extremely high pressures, since at some point, the concentration of oxygen will be so high that you no longer have an ideally dilute solution. But it should hold up around 1520 Torr, where at 21°C the oxygen solubility should be roughly 18 mg/L.
Look for a high-pressure empirical solubility equation in the engineering literature if you need more than a back-of-the-envelope estimate.
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