You could pull a CarFax report. Don’t those show the mileage any time they take it in to a place the reports those types of things. That’d be a dead giveaway.
I’d say go take a look at it. It could very well be correct and owned by someone that didn’t use it very often. Plenty of people have a pick up truck just for pickup truck stuff, but have a daily driver as well. And, if you’re going to have a spare vehicle, a Ranger is a nice little truck.
The only thing (other than something fraudulent) that would concern me is if those 12000 miles are 12,000 hard miles. That is, if it spent it’s entire life putting on 5 or 10 miles a day, all short drives, all heavily loaded up. For example, moving equipment or materials around in an industrial setting.
Also, if there’s any evidence of it ever being a plow, just walk away. You don’t want a used plow, unless you’re going to put your own blade on it. The miles don’t get much harder than that, plows turn into piles or rust extraordinarily fast.
ETA; it could have also just been parked for a while.