SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68a57782fdfe9bc8dfadcdac948ce5f7fe4800375431e79c963f1d11436b6168' 
  AND token = 'JVuyDt7ItLmgEkatwoRmx0vpfRjUGhKlZwUNjVx7x0U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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