SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '638729e6a385db536c8ed4f1f608eefdbfa84f7e1383a76f510bd5044bea4688' 
  AND token = 'LSJ8rxcBEgNeS0GoQB1dKnpCjeVf+FIn5DyPpP6Cx2Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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