SELECT 
  CONCAT(u.firstname, ' ', u.lastname) as author, 
  b.page_id 
FROM 
  cscart_blog_authors as b 
  LEFT JOIN cscart_users as u ON b.user_id = u.user_id 
WHERE 
  b.page_id IN (
    78, 74, 73, 72, 71, 60, 61, 62, 63, 64, 65, 
    66, 67, 68, 69, 70, 59, 58, 55, 56, 52, 
    53, 54, 50, 51, 49, 47, 48, 10, 9, 8
  )

Query time 0.00055

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.04543684,
    "nested_loop": [
      {
        "table": {
          "table_name": "b",
          "access_type": "ALL",
          "possible_keys": ["PRIMARY"],
          "loops": 1,
          "rows": 32,
          "cost": 0.0160708,
          "filtered": 96.875,
          "attached_condition": "b.page_id in (78,74,73,72,71,60,61,62,63,64,65,66,67,68,69,70,59,58,55,56,52,53,54,50,51,49,47,48,10,9,8)"
        }
      },
      {
        "table": {
          "table_name": "u",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["user_id"],
          "ref": ["u985510652_ecartify_dev.b.user_id"],
          "loops": 31,
          "rows": 1,
          "cost": 0.02936604,
          "filtered": 100
        }
      }
    ]
  }
}

Result

author page_id
Adminasdsadasd Admin 8
Adminasdsadasd Admin 9
Adminasdsadasd Admin 10
Adminasdsadasd Admin 47
Adminasdsadasd Admin 48
Adminasdsadasd Admin 49
Adminasdsadasd Admin 50
Adminasdsadasd Admin 51
Adminasdsadasd Admin 52
Adminasdsadasd Admin 53
Adminasdsadasd Admin 54
Adminasdsadasd Admin 55
Adminasdsadasd Admin 56
Adminasdsadasd Admin 58
Adminasdsadasd Admin 59
Adminasdsadasd Admin 60
Adminasdsadasd Admin 61
Adminasdsadasd Admin 62
Adminasdsadasd Admin 63
Adminasdsadasd Admin 64
Adminasdsadasd Admin 65
Adminasdsadasd Admin 66
Adminasdsadasd Admin 67
Adminasdsadasd Admin 68
Adminasdsadasd Admin 69
Adminasdsadasd Admin 70
Adminasdsadasd Admin 71
Adminasdsadasd Admin 72
Adminasdsadasd Admin 73
Adminasdsadasd Admin 74
Adminasdsadasd Admin 78