SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '204cca05c199a97c50a6e04b74391fde8867cf5116bdf4a7d9862a3277a397b8' 
  AND token = 'nxlnprhObXqN6iEVfrnQZmuXZ9qpbd/2mZS/JXucpbw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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