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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '256756c921e10e3d80f3ad5d8b0766beeda6dec288019fc000cf46a73c1fa90f' 
  AND token = 'Vm7eEXcjWNMIKavtDkSOIBoiMuC7QDvBJnT5zPwdBRA=' 
  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