SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '968b9b5350fed5621668c33b42cfdd254c3f320ebb0e4d994cd57410152cc2bf' 
  AND token = 'GdBJIYEBY6W40HnxRsYmrrRw2dJ+xhrzTpfnoKD+klo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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