SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '373c5d7591debbfc644b551b5725568c7a0d08c4e8f471366e645f3b98a3a302' 
  AND token = 'ioYLXpmJ7eCJ/IJixkDVh7eziDXEvYobFmLDgzMgDL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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