Keyframe navigator

After you set the initial keyframe for a clip, and if the keyframe button is pressed, Premiere displays the keyframe navigator, which you can use to move from keyframe to keyframe or to set or remove keyframes. A checkmark in the keyframe navigator box indicates that the edit line lies precisely at a keyframe for that clip. When the box contains no checkmark, the edit line lies between keyframes.

Applying Effects > Working with keyframes > Keyframe navigator