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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75ded814d4183f1322ec04d45415f9195b66b30a84bbc8f4ce88726748c0802b' 
  AND token = 'uIk86BPz14T8hdQjR8MZhqui4IGNg8hJMXmPjNiZiJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00011

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