SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4ccc21108eb99df4e1b7855f097f3a344feb37402329151f910aeb41d2ce973' 
  AND token = 'gWZ0BmKTy2wRKxOCATgJrb5MUKrmZrDC27Oq6IYbRcM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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