The SMART criteria stand for Specific, Measurable, Achievable, Relevant, and Time$-$bound. Among the options provided, "Search query must execute within two seconds at least $97\%$ of the time" is a SMART requirement because it is:

Specific: It specifies the performance expectation for the search query execution time.

Measurable: It provides a measurable criterion $($two seconds$)$ for the search query execution time.

Achievable: It sets a realistic expectation $(97\%$ of the time$)$ for the search query execution.

Relevant: It is relevant to the system's performance.

Time$-$bound: It includes a timeframe $($two seconds$)$ within which the search query should execute.

Therefore, "Search query must execute within two seconds at least $97\%$ of the time" aligns with the SMART requirement criteria.