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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f5aad5944ee7c66a2bfe1fd5d0755fbce870d7b1ddabe58d545c3ce3bd7b43e' 
  AND token = '6IjA0UeZQWuiDWB9kw7R9EK3sBrNRxCr5V3c92Su75s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

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