SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b73261605173e8617494e19d874854069b571b0b7922462f391d3104acbc20fa' 
  AND token = 'rVNOz+yBKJw2ciXV1ydxSleZsx19Va3mjxoXlBUlvFA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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