SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1e2da2392249a13d24519d60b3bd39886bab292d467cdc450557cd2b1b3e1ac1' 
  AND token = 'xf8fE1o2d1pZo9LVuCmH75v7mQvKqdQcjGtSHdzWuns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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