SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a9f21ddfc1edd5685504f4960883e3124001dd1499223f329467618d9259642' 
  AND token = 'Qf4w10jHBBUO9FXR5tEkTBj30m5Mnw7WMPDBnWQaeYg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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