SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bcea66e4537ee9f60b36a110be65d599b6f1602d54d467654ff90d33f7178a8e' 
  AND token = 'IMqE7nOpm4l0WEzRJD4wsWhD/Xh58lNevIHwBVpXeIg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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