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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6e6a6b25a45b860bae294ed0edb42d71f8ab289d7c7ac8c3acd8925301a542b' 
  AND token = 'plG8HGkoPvsIX1HA1hHr5TC9jFDyWZpYn9FCQyeJQ44=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

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