SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84b27bf54de56001c8785271390347a8cd52f709d09de47b0c94b95208fcbe52' 
  AND token = 'u6s83iPBdG7oJDNYTFQbBD/AjE0CX/enEyZec15X/jc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

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