SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a82faa1a761299fbf692892d43b1bef2979b139337bf2b53d1de5578d8f1bd75' 
  AND token = 'cDeUg0Y5zfSWi78ichj7sFwCH0IOlR7KQtrHcwKpK1k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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