Fix 500 error caused by range much bigger then actual array

What does this MR do?

During fixing error in !21049 (merged) I didn't notice edge case when there is actually much less Active Sessions than limit. It causes error - when there are more of lookup keys for a user than limit, but number of active sessions are smaller than limit we were ending up with wanting to get active sessions outside of range, which is causing NoMethodError. This fixes this error.

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Does this MR meet the acceptance criteria?

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