SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a6827343723ec255a14b02599cbd3280d7a1259b4ca1232dccd615d63888294' 
  AND token = 'EH0d6EXOsocEo45aniEihq3SWIIbHnlHVIClv5oDUsU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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