SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '516ff6f4f2893bdaefd21de36859cb7ac4617a49139266f06124737ddbf6b8f7' 
  AND token = '5jPT/xHF0UlOrOZeWq8uZIeYc58zKrppTzZwm3iSsYs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}