SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99020ad5ec34da575cad0beab2beb23cc859addb3746ae71a04676ed49ead17b' 
  AND token = 'DZoowgA8h4seANblDpsV/4YRgYnU/nu2ryEyyq7L1f4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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