SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50285e6109c93b65b21a7b22294bb7549cc0814b4a1c9d2da2d75419e7e742a0' 
  AND token = 'ZahNxZPTmR/MT5mo3A0JJnrkEkAprHR7a/d03sjEN5A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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