The key unlocks mordreds secret lab. You can get there by seperating the two hay bales.
The key on the big asteroid in Astro Knights Poptropica is located in the lower right corner of the asteroid near the entrance to the base. You need to use the bridge to reach it, but be careful of the falling debris.
Go to the place where the order is in. Talk to the guy with pimples on his face. He gives you the key. That is how to get the key for astro knights on poptropica.
it's in the astro belt at the bottom left coner area.you have to defeat the planets and have all the knights with you to get to the castle. once you have all the knights with you go to the astro belt then, go to the sword key and pull it out. after that you jump in the spining wheel thing.
you go into the portal. then you go to the bottom and talk to the princess.
It is under the things of hay. Get the key, the unlock the thing underneath the hay, then go to the left and get the owl.
defeat 1 boss in each planet (with the mystical weapons) and they come in your rocket ship (there are three knights) and then go to the planet where the key is (X-11 Y-83)
you just click it.
The small key in Astro Knights Island is for Mordred's secret hideout. When you come to that wind mill area, move the hay bales apart and use the key on that.
the door that's locked
You need to go to each planet and beat the creatures and then get the three knights. Then go to the place where you saw the key and you will see (the thing was that you needed those three knights). BTW - ONCE YOU PULL OUT THE KEY, IT WILL BRING YOU TO ANOTHER GALAXY!
you should've gotten the robotic mouse, give it to the robotic owl and go on from there.
Nothing, actually. Hidden between the two bales (trapped between the rocks) is Mordred's secret laboratory entrance. You will need a key.