SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50d706780564f96533ab96b2b16a858fb57b0f17913850a3d93790d23bdbe1e0' 
  AND token = '/q7fh2jsIQE9MHfIzhwfEHzBaU2KvVuUNBHgSFLZE38=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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