SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2436feb6f5e41bdddb9a87bfff429fcf0f7d7425e8997395ef80bb38b5e8205d' 
  AND token = 'xx7YNTNwEUIeTsEmkMKVUtbBqdIv8F2DC6Z59xrqgEM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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