ORIGINAL SOLUTION:
Title is slightly misleading. You do not have to be in a mission for an hour or longer yourself, you just need to be in a mission that ends with the total mission time being an hour long or more.
Therein, to get this one quickly, you can join a game that's already in the works, that's close to or over an hour long, and get the achievement once the Mission is completed.
EDIT ON 3/10/2022
Comments below indicate that the trick above is not working for everybody (I've read a few threads about discrepancies between host and client timers that may be the cause of this, though I have no direct evidence). If you're one of the unfortunate ones that can't unlock the achievement with the trick above, you can easily brute force this achievement, abet it will take you an hour to do so.
Start a private solo mission, and select the easiest Mining Expedition you can (preferably Difficulty lvl 1, Length lvl 1, Complexity lvl 1). From here, complete the level to the point where you would summon the evacuation dropship, with the following changes:
1.) Use your pickaxe during the level as much as possible to avoid ammo use
2.) Let BOSCO do the majority of the shooting for you
3.) Be sure to mine all the Nitra you come across
Now, once you're at the point you'd normally summon the dropship, feel free to summon all the resupplies you can into your immediate area, and just wait for the mission timer to hit one hour. Between the healing and ammo the resupply pods offer, and the assistance of BOSCO, you should have no issues holding off the occasional bug wave. Once the hour hits, finish the mission and the achievement will unlock.