SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '398f89ae35d55e7df0e5f719211be1cdbb0f23bc117b3377053b87fb2221e91c' 
  AND token = 'U6lmKGOGEUZtD2XtmjHEzrl21FFNfhZGafm/SpHGj9A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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