SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79168a1c82e504e9d3d575e5455f1157ce754cc2bf744a54850d3fcd70e81a6d' 
  AND token = 'tTlZfLyRemjvwtHM9YwhWQ4fG9bZtK/DOAtrNS+ap8E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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