SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2c5f9e5a21896007d89e27f59b30dbdfdd6463d33473b65413328add98b9a263' 
  AND token = 'RzRuPuiLNxRpNjr/Zr+OzolkVKk7qq06RO2XgtaisOc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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