SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b8b7d2f2eed9a88b7adc72da8c4ec10aad5a39dca631548bf43f2adb6167f529' 
  AND token = 'viCB8iAHV94oqIAjz/vHaaJ/lK/lzX9J4L4rfcC+nWY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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