Air tends to be 80% N2 and 20% O2.
Acording to NIST, at 250 psia, air will not liquify until -251F so now I understand your question.
I just don't have any idea how to find the Henry's Law constant for air and liquid CO2. None of my resources have anything about liquid CO2 at all. The detailed study the effects of changing temperature of pure water on the rate of solubility is the subject of conflicting papers, I don't think that this topic has reached the maturity where anyone is looking at different solutes. Sorry.
David