This concerns closures by 1 user + 1 moderator, but what when 1 moderator closes? This obviously appears less democratic.
This is absolutely by design, and perfectly democratic. Moderators are elected (or in the case of beta sites nominated) based on their ability to make the site "better" and Stack Exchange has been explicit that if a moderator thinks a question should be closed (because it doesn't meet requirements or is outside scope) then they should close it.
If a mod is in doubt, often they will wait until other close votes are on (I do this myself sometimes) to bring the effective value of their vote down to one ordinary vote.
Yes, they are allowed to do that, and therefore are required to be more careful before making a decision.
And you are free to contest their decision on any particular question that was unilaterally closed or deleted, by asking on meta.
If the community members disagree with a mod action, they can help reopen it (but not undelete)
A moderator will close down a question with a binding vote (irrespective of the number of close votes it has already collected, whether 0 or 4) only when they are absolutely sure that the question needs to be closed.
If they are sure, they are empowered to act, even if they would be casting the first close-vote and thus closing the Q with a single vote.
Note too that it is not a question of democratic, but about moderators performing their duties to the best of their abilities, fulfilling the legitimate expectations of the community and implementing the guiding principles of the Company. I have almost never seen a moderator misusing this serious responsibility while unilaterally voting a question closed.
Again, closed questions can be reopened by the community with 5 reopen votes and by a moderator with a single binding reopen vote. So the whole process is reversible if there is good reason to do so!