SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20f274fd98265acca247e4f8bc574f7421f05602b83821c62e4acdf9ffb7863d' 
  AND token = '9GZsSIuLL5z8lUwjDTbOJSKd608sKFSF4vNaU/bDY9M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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