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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78f1dced0569e0e16a5bdfb3402fc485242116901dae2a625b6c9b3572acb4da' 
  AND token = 'YGZXhQTnU19YLayU8lflX8Q+4Pvl0+6H/h4+uGQDExE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

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