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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '571cd17dd4d5e5a0e792b487f005ba36b0e7dd798a0db48999686ccbb0078566' 
  AND token = 'viXWzXxqTn8l7DW4gnhG5zCXSOnCZjVT3Vm0PrIQxns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

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