I got the 444 class trinket from week one’s vault this season, it is not that good in keys unfortunately. In keys you need short burst 
CDs non stop (20 sec CD spriest instant aoe dot and instant machine gun/sensor missile mind blast!), which warlock simply don’t have. You can’t combat the fact that spriests not only have way more utilities, they are just superior in all aspects and we are competing for that one caster spot with the absolute SSS+ spec not by skills but competing with the miserable case of the failed class balancing.
Regarding the comment on warlock is good in raid so if they buff us in M+ we would be too good in raid, I completely disagree. We are weak on aoe, in keys, and good on ST. In raid ppl only look at overall boss dmg but in keys it’s overall dmg including trash, to show up high on overall dmg you have to tap on those trash asap and burst them down to contribute to your overall numbers, we are always lower than high mobile high burst classes period, ramp up is too slow, unless you are running with 4 friends and you guys are highly highly coordinated, which is not the case for most of us, buffing aoe won’t effect performance in raid at all, we don’t even talent into ROF or Implosion in raid, irrelevant, just leave ST alone and reimagine our aoe, buff demo’s aoe numbers, change destro’s aoe style so it’s not cancelled as soon as the group is moved, which is the core mech in M+, MOVING.
Update: just did a M+ with a fully geared demo lock, he got 6 PIs and used 3 ultimate potions of power for the run, when I didn’t even use a phial, I am 436 ilvl and he is 442+, he barely did 5K overall than me with all that buff. AND I was doing the affix.