SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '991ebbec53b67fc03386387bf6f153cb6e06f4cd0335031718b9da2cc9597564' 
  AND token = '104CTUjZzoD44psdIvIE7UEKKNBBE4bgvy2jM/alHms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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