Never mind my previous post if you read it, I was wrong 🙂
I've changed the keyword logic on the General Options -> Behavior panel, to AND, as it fits more your case. The default “OR” logic is designed more for small databases. I believe it's going to give you much more accurate results now.
If you need more information about keyword logics you can read it in the documenation.Best,
If you like my products, don't forget to rate them on codecanyon :)