SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8b5220659fa4735d12c456543d49a51842e8881fc910cabadef3529e4aa1003' 
  AND token = 'a0ObZ02sE9Yp3YA1EluO50a+EfLcPDikTDKgI7NCKjg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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