SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '399868b5e969913e31b54f5500486784f557858eeb474b4d18b6353358fb26d4' 
  AND token = 'AHJx4hX0sjWvuzNpK22jtXYTaUpFAY7wounBgNgmBbs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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