Frankly, it entirely depends on how you build the warlock, and how the game is run by the GM. There's a lot of problems with the warlock when it comes to being able to use utility spells, and why short rests are so critical to the warlock. In general, my experience has shown that, in calm situations where there's not a lot of time crunch, the warlock has access to more magic utility than anyone else. There's no fear of flinging around Hexes or Charms to deplete your daily alotment when you're going to just be riding a horse for the next hour. But, when you're expecting encounter after encounter? You're suddenly a lot less flexible, and you have to hoard magic. So, yes, in this situation where you can't expect another short rest anytime soon, you are hit harder by dispell / counter magic, and that's only if you're relying on buffs and not offensive magic - one of my favorite tricks with the warlock is to use the Command spell to force enemies to runaway, provoking AoO. I get Eldritch Blasts thanks to Warcaster, our rogue gets to sneak attack, and the pally in the group smites. The scaling level means I always hit multiple enemies with that one.
Part of the reason why rings of spell storing, rod of the pact bearer, and the tiefling are such a huge boon to being a warlock - all those extra spells you can get in a pinch are a huge boon (though I do scale the damage from burning hands/hellish rebuke up with level, like cantrips). It gives you more flexibility and options.