Secure my API connection with other websites

Hi,

I'm using codeigniter-restserver library.

My goal is to give access to other websites to get some data from my DB.

So I need to secure my connection and make sure the website(which is willing to share with) access to my API.

I was reading the documentation and I found we can use rest_valid_logins by using username and password. but the thing is I want to make dynamic access to websites. I need to store accesses in my Database.

Then I found X-API-KEY which can store the keys in my database and give access to requests.

I would like to add another authorization to make sure the key is using only for one website not many. I want to check 2 things at the same time like X-API-KEY with the Website domain name.

How should I make this happen?

Thanks guys