SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76d8df94a1e920f8a7003746f1789b5dbfac02c7333af0bf46e00bbad19cbcf6' 
  AND token = '3DhYSTZntlwSAhQwEWqVLBsmtvio/pPVgOoVEqTt9P0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}