SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99b0f173690694acfa4053a985d62ccb5ef13e3fb69af277b95fcc863ca01768' 
  AND token = 'M81AFwFadVZu2MLGaY0qIxB+MbM/5E8ThBQGBhH4/2k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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