If someone was able to request your Google Maps location, they either lucked out and guessed your Gmail address or found it on one of your social media accounts. In any case, you ought to review all the places online that you may have shared your Google email address or the phone number associated with Google Maps. Consider removing these details from public view or using a different email address and phone number if sharing your contact information cannot be avoid. Alternatively, if you have the option, set your accounts and personal information to only be viewable by those you approve to be connected with.
It is important to note that only people who share their location with you should have the ability to request you for yours. If you received an email notification requesting access to your whereabouts, you probably also received a notification email letting you know that the person shared theirs with you. They will be required to show you their email address and profile photo. While these two things can easily be faked, at the very least, if you have to, you’ll be able confirm with friends and family that the accounts indeed belong to them and are not fakes.