SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '171475b5ab6dc3dda782af43a1cbd38292ebd466e1da435309d9176244042e50' 
  AND token = 'TwA80gDKV/oD23netiBwPRnmFLS9qUBF6rVcm891Aho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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