SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '208f1c70ed2f023761dd6ff2f79d705d2540b050aadc9a3ea59e6ec906172a80' 
  AND token = 'H+kVRuxAnK/FUiz82XW2BjL9w/tqgF0+qNhd5xNSlRc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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