SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b256caf8dd7187dff587367ad4705d959bce43bbd5b4eaa59583e3229ecd37a1' 
  AND token = 'oGzb7ld+ccQO4YPsvGVv8IXgtqdi4IY+pPCFgs+CZmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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