IIRC the secret to Concorde was a modest static engine pressure ratio. At cruising speed the OPR of the inlet/engine/exhaust system was high and it was very efficient without blowing up or melting the engine's hot end. The downside was that it was horrible at subsonic speed.
Concorde still holds the record for unrefuelled supersonic range, and by quite a big margin. Unless there is something we don't know about....