SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9740b64f4cdc190f55ffa24dcc6d6a0ef95d28379e27e682d7d7b048b5547cd0' 
  AND token = 'Q7upNZny1rVP3BpwuF1fxVGSRoEZKf/ZLQICDK5mmVw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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