SELECT 
  entry_page 
FROM 
  cscart_companies 
WHERE 
  company_id = 1 
  AND redirect_customer != 'Y'

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}