SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b494ee265a8bc5e1d167ac84fdf463f5d8f8be9b4a20701df348b2415beffbb7' 
  AND token = 'eHVGHhB73YF270wMDlunU2hVu0vcMo9XCELlQAJfq/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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