SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82716a4cc19336781726c59dbf4569b47d0dbf8314a2f4ff27d940d9065f68b4' 
  AND token = 'KuXnoJqYSP6UTcnY3dmf3zqyzQZepg+eswmVCNiHY3M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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