Do you feel that too? I can't shake this sense of impending...

Well, that's pretty straightforward, but there is one catch: there is no way to tell package number(SubID) prior to activation. But I'm jumping the gun. First a few common points:

• Every steam key actually activates not a game (AppID), but package (SubID). Package may have one or more games, and may or may not have restrictions. There is no way to find SubID of particular key except of activation, and even then it's not that easy; for example SteamDB web extension shows steam package activated on account; or you can use steam console to find out packages, activated on account (I never did it actually, just heard of it, but I think it must work); and, what I would actually do, if I ever decide to find out package by activating the key - ASF shows package ID right after activation, like this:

  Status: OK/NoDetail | Items: [8566, Syberia]

• Even without knowing package number, you can guess one - for example, if there is a package, that can only be activated in a number of countries, and your country is in this list - then there is a high chance you will get this package (unless it is known that you buy from totally disregards it). So, in most cases, if you don't know for sure - it's better to expect worst-case scenario.

Now directly to what steamlocked.com shows you in "RAW Data" section. It's a data, retrieved directly from steam (slightly re-worded in case of steamlocked.com, but still), so this data will be the same on other steam tools, for example on steamdb.info. I will explain in steamlocked.com terms.

• Package may be restricted in two ways - it may have a list of countries where activation is ALLOWED (and it can not be activated in other countries), or it may have a list of countries where activation is NOT ALLOWED (and it can only be activated in other countries). Apart of activation restrictions, it may also have restrictions on RUNNING in selected countries (so, even if you have activated this package from one of those countries - you won't be able to RUN this game when being abroad). Some examples below (I will take the same https://steamlocked.com/app/379720 as an example):

SubID: |    70918 
Package name:   -
Billingtype:    Store & CD-Key
Cross region gifting and trading:   Blocked
Banned countries:   DE

In this example there is a Banned countries: field. This is a case when ACTIVATION in NOT ALLOWED in a list of countries. In this example there is only one country where game can't be activated - Germany (DE). Obviously, if you've bought this game in Germany - you can be sure this is not the case)

SubID:  99365 | SteamDB
Package name:   -
Billingtype:    CD-Key
Cross region gifting and trading:   Blocked
Countries allowed to activate:  RU AM AZ BY GE KZ KG MD TJ TM UZ UA
Countries allowed to run:   RU AM AZ BY GE KZ KG MD TJ TM UZ UA

In this example we have both Countries allowed to activate and Countries allowed to run:. Countries allowed to activate has a list of countries, where it is ALLOWED to ACTIVATE this package. You won't be able to activate this game from any other country. Countries allowed to run has a list of countries, where it is ALLOWED to RUN this package. So, if someone bought a game in Russia(RU), activated it on their account, and then decided to travel to Australia - they won't be able to play this game until they return back to Russia (or any other country from this list, actually, so they can go to Armenia(AM) and will be able to run the game there).

SubID:  100707 | SteamDB
Package name:   -
Billingtype:    CD-Key
Cross region gifting and trading:   Blocked
Countries allowed to activate:  BS PA BZ CR SV GT HN NI VE CO GY SR GF BR PE BO PY UY AR CL EC MX

This has only Countries allowed to activate:, so if your country is NOT from the list above - you won't be able to activate it, but if you've travel to Bahamas (BS), bought game in local shop and activated it while being there (you would have to change shop region in steam store too, probably), and then returned to your country - game will still be playable.

And that's pretty much it. So, if you're not from BS PA BZ CR SV GT HN NI VE CO GY SR GF BR PE BO PY UY AR CL EC MX + RU AM AZ BY GE KZ KG MD TJ TM UZ UA, then your only concern - can this game be activated in Germany (DE) or not. And, as I said above, there is no way to tell for sure, unless you bought another key and activated it yourself to find out what package it has.

TL;DR: Look for packages with Countries allowed to activate, Countries allowed to run: or Banned countries: to find out about possible restrictions.