For a fixed gear, forget about multi-speed chains (they are thinner, less durable, more wear just to be slim enough to fit the small gap between cogs, and also later weakness so it can flex to shift).

You need a solid "one speed" chain, like 1/8" chains, and I'd be looking into Yaban.. they make professional industrial chains, and bicycle chains also. So far Yaban chains are proven to be bulletproof in terms of stregth, and since FG chains are seriously abused, a snap of the chain should be avoided as much as possible, so for this go with a regular bushed strong chain (even if it is a bit heavier) from yaban for example.