I will be the first to admit that I have NO idea what a 'Lower Keys' corn snake looks like. Every corn snake I have ever heard about coming from the Florida keys seems to be called an Upper Keys Corn. Not sure exactly why that is. Either the Upper Keys are just teeming with corn snakes that the Lower Keys lack (which is sort of consistent with the fact that the corns from the Lower Keys are protected), or many people think that the Upper Keys begin with Key West and extend to the mainland. Seriously, I do suspect that each of the major keys in the Florida Keys might have it's own minor variations in the way the corn snakes coming from them appear, but unless you yourself go down there and catch them, or get them from someone entirely trustworthy, I would take such information with a big grain of salt.
The Upper Keys Corn is kind of hard to describe. In some instances it looks like something inbetween a hypomelanistic corn and a regular Miami Phase corn. There is usually very little contrast between the blotches and ground color. And often the abdomen can be pretty much patternless. Kind of long and lanky of body shape, looking a bit more streamlined that the typical corn. Nearly all of my examples are very mellow acting animals, and in some respects act very similar to the Amber corns in personality.
One interesting bit of information is that I have had some apparently Anerythristic looking babies hatch out of the line I have. The guy I got them from (Craig Boyd) said they were wild caught animals, so this is an interesting development. This is probably just some 'A' Anerythrism popping up, but I have never heard of them coming from the Keys. I certainly hope so, since the last thing we need is yet another genetic form of apparent Anerythrism!