SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1738ad6867fe4843ed622b08f668842fb51bd687b649fdc24cc7aa8356ec4475' 
  AND token = '7NJfpK1PRMKmFtFiRPTpi4muNpUBOBVSiAkLP2x+kGs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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