SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cad9b315c7625b1349c92961ba0374452e9750347c449e111d269b5013db1d5b' 
  AND token = 'bDkjWqFg/zyBkw+zMyKbghRAHFTML8ENJRe+YXkigVk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}