SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4b882159f53623d3d65f94c1d1115f28732506adf612e1bedacfc086ef3f66a' 
  AND token = '+q0CAm17k7cDc/ZWUZcnUhOqDjVJCBkiVdZ9n+vKD/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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