SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '291a2ecd8012271035cbb9bb80c8be4ce602f293fe5a67b95b4988e7ef114a3b' 
  AND token = 'gb3nM/ZO5U+GpZQehMVhn3XRxFPIv4iRgxwnBGcOla4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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