I stand to be corrected by the real Concorde experts who flew it on this site
From what I’ve read Concorde would climb at VMO with afterburners engaged until reaching M1.7 at FL450 at which point the AB was turned off and VMO maintained until reaching M2 around FL500 then cruise climbing at M2
From the graph it looks like 530 KIAS would be on the VMO profile at FL450