Good deal for those that want Lobi.
This deal is cheaper per Lobi than the Lockboxes.
Not by much and only if you're only planning to open one or two. On average I think opening 10 or more lockboxes it's assumed you're average lobi per box is going to be around 5 or so. I did the math and assuming you're buying individual keys instead of the 10 pack the static 10 this rewards is only cheaper if your lockbox Lobi average is less than 4.5 lobi per box.
It's still a much better deal than buying two keys and hoping you get something really awesome in and of itself, but if Lobi is the only reason you're buying and opening these things you're probably better served buying a couple of ten packs of keys or just grinding the EC to buy them off the exchange.