SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8921e3558c4eb2bf0828855bd763e3a18cea1cda1824df10bb86f25af142190' 
  AND token = 'ctUMSqYRVHP5UYOFrVWI8F/QZr08slvB8D6z9TTd5Is=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

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