SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1dffc9da14dbed950d9556f709375d863250377782283ff29d312f6902a9bff8' 
  AND token = 'IDeOuvggxs1kSUJKlHnlqrTOtAkh4OYYt/iQUDtKS0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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