SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0f21d455d9c9a83111c2529444e2054ed52434096799d97afd6cf35b9a88a1d1' 
  AND token = 'uBqdxR3mudKzXuOFtTUCAQtueQePzZmRPpUmmCpIoXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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