SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b97a3094210396ac17cbd067515ac219632068e9bcbdcae7bde7d7980a8119c2' 
  AND token = 'vRVu2pGEmSSQJAwmLLWi7f8nR9+lGktBRWgXfEhcQOI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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