SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a313677defad6c445fd10cfbce73f18de908f2ee466950c97063149401ea41b7' 
  AND token = '7nSoGMHXamVpfjAeywUSwqo+w2wtnRYijCyJnOZFJjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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