SELECT 
  field_id, 
  value 
FROM 
  vi_yl_vipiris_entity_field_values 
WHERE 
  entity_type = 'pages' 
  AND entity_id = 20 
  AND lang_code = 'en'

Query time 0.00010

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "vi_yl_vipiris_entity_field_values",
          "access_type": "ref",
          "possible_keys": ["PRIMARY", "entity_lookup"],
          "key": "PRIMARY",
          "key_length": "102",
          "used_key_parts": ["entity_type", "entity_id"],
          "ref": ["const", "const"],
          "rows": 1,
          "filtered": 100,
          "attached_condition": "vi_yl_vipiris_entity_field_values.entity_type = 'pages' and vi_yl_vipiris_entity_field_values.lang_code = 'en'"
        }
      }
    ]
  }
}