SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9af24c86ab08ec28db71b8e8814ad56fcedf20f0ee8860ddbf944f89f5ee064f' 
  AND token = '6cYS4n9DJPz2PFM3FtLRm+LUPvCjPVU+PNY+KTuw4pg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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