I have some points result query in MySQL database which is GeoJSON and I want to show these points on a Google map. I need to get this result with AJAX and deliver them to Google Maps. Can anybody write a code to do this?
Google Maps Platform has extensive documentation on using GeoJSON data.
Although it is not a Google map, you could try looking into the Leaflet package which has support for GeoJSON objects. You can then build the appropriate AJAX calls around it to get the data you need.
If you just want to look at the data visually (and are not really building a web service), geojson.io is a great place to upload and inspect reasonably small geo files