SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3bdd9df79eefd459587e19a9f3fa17d574eb9ec744f77b32955d46eb462a6e31' 
  AND token = 'Vtwqo8F+XELHiwvsFiLLmgFCVrnJ4p3KYjmJUu2T3uw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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