SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a90d2aebef5e6b44480046d3c328923ccc528697bb50fa74d77fd48f6ab8683' 
  AND token = 'Btsr+RNsHZbPaajeFnj5gUeRRBE5HUqFGHAunIMbLdw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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