SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70811ac7083795fa231714cfa0f707103aa9b52b5fea7499b8c6c659160a730c' 
  AND token = '9n2kS5PXPsxyR5MjlHnH44u42afUh0BupjFajFz13s8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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