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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5684d00ed748a01f7ed2028eb00d2642bfc396c2edbf0c981d32359f09743f9c' 
  AND token = 'B+WcLbf1cc1A7eROR+rzO0QINwb1Xwhr8K5N0VjrXAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

Explain
id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
1	SIMPLE								Impossible WHERE noticed after reading const tables