SELECT 
  COUNT(*) 
FROM 
  cscart_ec_booking_events 
WHERE 
  layout_id = 1 
  AND status = 'A' 
  AND event_start_ts >= 1781109648

Query time 0.00052

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "1.20"
    },
    "table": {
      "table_name": "cscart_ec_booking_events",
      "access_type": "ref",
      "possible_keys": [
        "idx_layout_id"
      ],
      "key": "idx_layout_id",
      "used_key_parts": [
        "layout_id"
      ],
      "key_length": "4",
      "ref": [
        "const"
      ],
      "rows_examined_per_scan": 1,
      "rows_produced_per_join": 0,
      "filtered": "33.33",
      "cost_info": {
        "read_cost": "1.00",
        "eval_cost": "0.07",
        "prefix_cost": "1.20",
        "data_read_per_join": "280"
      },
      "used_columns": [
        "layout_id",
        "event_start_ts",
        "status"
      ],
      "attached_condition": "((`pankajecarter_setup3`.`cscart_ec_booking_events`.`status` = 'A') and (`pankajecarter_setup3`.`cscart_ec_booking_events`.`event_start_ts` >= 1781109648))"
    }
  }
}