SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4368d4ba03937130603f408b82453c390626c2b41b5d44b904a7405f0195c7dc' 
  AND token = 'hU93SFzAACNT1x8WgJY+vOJgHOFXBAchCkBQTIOYw4k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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