Hello Soh,

this verse is a draw because it tells us of how tough it is to find time to "stand and stare." You also talked of the irreversible time, hence the lesson to make the best use of it.
The tone-
mood is helplessness at the fast pace of life, and tone, one of remorse. You can't stop the passing moments, you can't hold a moonbeam in the palm.
"I wish
For time to stand still
Because I want to live the moment of silence,"
Moments of silence are an impossible commodity to enjoy in the rush and din of life. We don't have peaceful avenues nor vistas of beauty anymore in our cities, the concrete jungles.

Imagery-
imagery shows a person tired of running the race of life, someone who wants to stop by the oasis of silence in the desert of restless life.

Nice poem.

Write on!