SELECT 
  value 
FROM 
  cscart_form_options 
WHERE 
  element_type = 'U' 
  AND page_id = 45

Query time 0.00015

JSON explain

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