SELECT 
  cscart_profile_fields.*, 
  cscart_profile_field_descriptions.description, 
  cscart_profile_fields.checkout_required as required 
FROM 
  cscart_profile_fields 
  LEFT JOIN cscart_profile_field_descriptions ON cscart_profile_field_descriptions.object_id = cscart_profile_fields.field_id 
  AND cscart_profile_field_descriptions.object_type = 'F' 
  AND lang_code = 'fr' 
WHERE 
  1 = 1 
  AND cscart_profile_fields.profile_type = 'U' 
  AND cscart_profile_fields.checkout_show = 'Y' 
  AND (
    cscart_profile_fields.field_type != 'E' 
    OR cscart_profile_fields.section != 'C' 
    AND cscart_profile_fields.field_type = 'E'
  ) 
ORDER BY 
  cscart_profile_fields.position

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "read_sorted_file": {
      "filesort": {
        "sort_key": "cscart_profile_fields.position",
        "table": {
          "table_name": "cscart_profile_fields",
          "access_type": "ALL",
          "possible_keys": ["checkout_show"],
          "rows": 64,
          "filtered": 28.125,
          "attached_condition": "cscart_profile_fields.profile_type = 'U' and cscart_profile_fields.checkout_show = 'Y' and (cscart_profile_fields.field_type <> 'E' or cscart_profile_fields.section <> 'C' and cscart_profile_fields.field_type = 'E')"
        }
      }
    },
    "table": {
      "table_name": "cscart_profile_field_descriptions",
      "access_type": "eq_ref",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "12",
      "used_key_parts": ["object_id", "object_type", "lang_code"],
      "ref": ["multi_vendor.cscart_profile_fields.field_id", "const", "const"],
      "rows": 1,
      "filtered": 100,
      "attached_condition": "trigcond(cscart_profile_field_descriptions.object_type = 'F' and cscart_profile_field_descriptions.lang_code = 'fr')"
    }
  }
}