SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8acb00ca7fe81d43a8716f100155a9f5bb59825d71be8588ec948450775498e' 
  AND token = '8PIz4wyuuhzciMsTDutaUZIlqJUCdNGGyg632147RN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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