SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71afef970d723ceb712e93d73a7fe2553ad43a7eaca4fbca836135b22cd7149f' 
  AND token = 'XWWsNm3FktiFQaJVf99MvfNn7NvcS+U8F/cSK6+xTZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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