China
The giant asteroid with the Golden Key is near X-11, Y-84, deep inside the Asteroid Belt. Only go there when you have defeated all three planets (Jungle, Ice, Fire) and have all three Space Knights with you. Only then can you draw the Golden Key from the crystal.
The Golden Key is Mordred's gateway to another galaxy, hidden on a giant asteroid in the asteroid belt (X-11 Y-82). In order to pull the Golden Key, you must have defeated all three planets (Jungle, Fire, and Ice) and have the three knights with you.
Yes, and the portal to the other galaxy is the Golden Key on the giant asteroid at X-11 Y-84 in the belt. You will need to beat all three planets (jungle, fire, ice) and have all three space knights with you to pull out the Golden Key.
The asteroid with the Golden Key is in the asteroid belt at X-11 Y-82. (This is in the lower left of the solar system.) You must have completed all three planets (jungle, ice, and fire) and have all three knights with you before going to the secret asteroid.
It is in the asteroid belt near the coordinates X-11 Y-84. *You cannot remove the Golden Key on the asteroid until you have defeated the three planets (jungle, fire, and ice) and have all three of the space knights with you.
Once you have completed the three planets (jungle, ice, fire), you will take the three knights to the secret asteroid in the asteroid belt. (X-11 Y-82) As the Chosen One, you can pull the Golden Key from the crystal, opening the portal to the Binary Bard's hideout in a distant galaxy. (see the related questions)
The Binary Bard is hiding in another galaxy, and the only portal is on a secret planetoid in the asteroid belt. There, a Golden Key opens the entrance to the portal. Before going to the asteroid, you must defeat all three planets (fire, jungle, and ice) and have all three knights with you, so that you can pull out the Golden Key.
The "giant asteroid" with the Crystal Portal is near X-11 Y-84 in the asteroid belt. Once you have defeated all 3 planets (jungle, ice, fire) and have all 3 space knights with you, you can travel there to pull out the Golden Key and follow the Binary bard to where the Princess is being kept.
The crystal gate, and its Golden Key, are on the giant asteroid at X-11 Y-82 in the asteroid belt. You should only go there when you have defeated the three planets (jungle, ice, and fire) and have all three of the space knights with you. Drawing out the Golden Key opens the portal to the other galaxy, where the Princess is being held.
In the asteroid belt, at X-11 Y-82. (This is in the lower left of the solar system.) You must have completed all three planets (jungle, ice, and fire) and have all three knights with you before going to the secret asteroid.
When you have defeated all 3 planets (jungle, ice, fire) and have all 3 knights with you, you can travel to the giant asteroid in the asteroid belt (X-11 Y-84). There you can pull out the Golden Key and enter the portal to the realm of the Binary Bard.
The portal is the connection to the "distant galaxy" where the Binary Bard has his castle. It is sealed with the Golden Key on an asteroid in the asteroid belt, near X-11 Y-84. Once you have beaten the three planets (jungle, ice, fire) and have all three space knights with you, you can go there draw out the Golden Key and enter the portal, to find the Bard and the kidnapped Princess.