SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4125f087331a7a3db3ef022ce36d0fa77b3261ae5de81b78d22304c918201858' 
  AND token = '9n5zrI/ZPEtgyJQhviRwmfVG/n7P0xRW1wh+hNza57Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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