SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '609f2d730314cfc98b06ec5bc0e705a5424fe6fd56420cab92dbd24e02324a21' 
  AND token = 'v7ml6mqQEEsiqDMLi6vZbzEDjdaTCjRHmyoUP6pJsAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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