Hi!
I’m assuming the book title is the same as the woocommerce product title? In that case, on the General Options -> Sources panel make sure to only have the Search in title option enabled, and the Search in content, Search in excerpt, Search in terms options are disabled: http://i.imgur.com/v1OhIbp.png
Please check this chapter in the documentation on how to improve search performance. It’s especially valuable if you are running on a shared, managed host.