SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '311df5b44b0ae158f9fdf6e3d4a4450557edecbe805c294376b24d085261278a' 
  AND token = 'KHcPdXz1qUUWcjWZ3anSjdvO3qMLxjIkdi+7CvCgw6g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}