SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd5dc6a2e874835044805c03d1e8e1095ade4c3c3519b66a63b82205a2935647' 
  AND token = 'NS/9zgi6FBV3ImVmVJny7JznDVXCF5YgwtA0xqNtN6g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

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