sure, the chain will be shorter too. But a 40t track ring is right up there with a 10t track cog.
Most of the track chainrings run higher baseline tooth counts (that sounds odd...don't it?). You can find smaller tooth count chainring in road/MTB applications. Hence teeth ratios common from track like 46-53:12-17, maybe even higher in the front ring, but most track racers do not run 18-23t cogs, at least the ones I know of.