Almost all tokens have a CMC of 0, so a newly played Ratchet Bomb can immediately kill them. The exception is tokens that are copies of creatures (via Rite of Replication or Cackling Counterpart, for instance). These tokens will have the same CMC as the creature they're copying.

Do token copies have the same CMC?

If a token is a copy of another permanent or card, then it has all of the characteristics of the original, including its mana cost. So, it's converted mana cost is the same as the converted mana cost of the original permanent.

Do copies copy CMC?

The copy will have the same CMC as whatever it's copying. This FAQ answers many of the common questions asked in the MTGS Rulings forum.