SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '497be777634086713bae22d39bb028d79320449a8664e360ed49664419abe50a' 
  AND token = 'kFB/CaA5Gm2GTcftGnlZPZGSgeWm7sxOmsFrWnWmkiY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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