SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '763ce3f6e5dbef92991e12ce06abddc3dbfb7ea36440409f96b26fd99effd8e2' 
  AND token = '4irJGiW6tkDgCRv5sS7/qNvEgWVLOXDGj3KOVnJjes0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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