The bout is widely regarded as a mismatch however Golovkin is available between 1/6 and 2/9, not the odds of a total mismatch, though he is obviously strongly favoured to win. Brook, the under-dog, has been priced between 4/1 and 5/1 and is viewed as a live under-dog at those prices.
The likely outcome of the bout is Golovkin by stoppage, which has been priced at between 1/3 and 4/11. The Kazakh claiming a decision is available at 13/2, suggesting that the bookies don't believe Brook can take the power of Golovkin.
For Brook to score a decision the odds, at best, are 9/1 whilst Brook by stoppage is a staggering 12/1/ Amazingly the draw is available at 50/1!
As for the over-under the general feeling is that the bout won't go over 8 rounds with most bookies suspecting it will end in either 7 or round 8. Of course that also means the bout isn't expected to go the distance, with most the odds on an early finish being 2/7 whilst the fight going the distance is 7/2.
Golovkin and Brook battle for Middleweight titles