SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9539f20c0fe537eb540e5de9207e37877765b623b3f702144c0c33ab600fbbf7' 
  AND token = 'OD1dj75wHruET8nfipOBpjueIOrx/sEqKDib5xHzaR4=' 
  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"
    }
  }
}