SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8c73966a1324066525fec928f62fb802f67603f96d7101297d7fa354d249d81' 
  AND token = '1r/2i571a+2IeEuiUZSHzyRyf0bGWZb30XmHnd7IFHk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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