Bancomer and Banamex offer safety deposit boxes. I believe you need an account in order to open one. I understand that they are quite safe and not to expensive.
Queretaro isn't to far. I would be very carefull about instaling a safe in my home. Nobody should know other than you and your immediate family.I think that availability via banks is very location dependent. Almost impossible if not impossible to find where we are, thus use of safe's.