Sorry if I wasn't clear. Since I was grinding 3* blue evo shards, they fall only in the regular LOL levels, so yes, I was referring to the level 10. Ended up getting 18 LoL dungeon keys from level 10, while grinding for magus evo shards.
Also, I noticed just 2 days before this awakening event, in the regular LOL levels, under rewards, there was a dungeon key.
I have seen some dungeon keys drop rarely in the expanded dungeon levels. So it's in both the regular level 10 and 11 & 12, also.
For the LoL awakening, going from character level 8 to 9 requires 100 3* color specific runes, and going from 9 to 10 requires 200 3* runes. So, since we have to grind for evo materials, we also earn keys. You shouldn't need to ever purchase any for FC in the store.
I currently have 22 total LoL dungeon keys, all earned while grinding.