Can firstOrCreate be treated atomically in Laravel?

I have an API that another application hooks into to upload some user data. Each peice of data belongs to a user and the user's email address is included in each API request. If the email doesn't exist in the users table then a new user is created, otherwise the new data will be added under the existing user.

I need to if firstOrCreate will be guarenteed to return a User object if two API request are made back to back. In my current code, I am querying the database and if it user doesn't exist I create one. But I am having an issue where if two API calls are made back to back, I get two inserts into the database (two users with the same email). I have since added a unique constraint on the email column but I want to be sure that if I use firstOrCreate I will be able to proceed after that knowing that I either have the existing user or I have successfully created on.

via Chebli Mohamed