Search Engines are funny. There is no one answer for all engines and the answer continues to change for each engine.
The most important factor still remains to be content and good naming. But I would say 5% of your score is name.
Artificial Intelligence (AI) can read a two word compound word very easy. So non-hyphen domains are preferred. But when you get above two words you begin to get into more complex AI. So hyphens may pay off until the engines get more complex.
If you can I would register cattoys.com, then cat-toys.com, and then kittycattoys.com.
I would go for cat-toys.com - I don't know that search engines spend the processing time to unravel compound names. My personal belief is that most of the advantage attributed to naming domains with keywords comes from the "link text" aspect, a keyword name makes that easier. Admittedly a hyphen in a name has some usability downsides (describing the name on the phone, etc.) but I think it is more likely to have an effect.