SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '759b4efcddb12e914b506affb4e1d58ebdd6b0654f93d1187974aef30d8cdbea' 
  AND token = 'KvGHYvGI2DK8F8/6tYBUvwjHrqCzHvMyyQSmiEtcZIk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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