SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3b9bf86c19028cec6a58a1f59a40a96246225a06afc760882f4687bc6a5b0e1' 
  AND token = 'GnXGsSglI/f9AIM+nlB0k1KhjZyi5aHBU3YkQ8CNtqA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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