SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd786721aa30b8738c54f3db04caa37dca7bad3905ec065dd26833234ff0f9708' 
  AND token = '4XXDMbWKAOfgXQPhFn+avnXquJvguL4EtI+z+O8g+rI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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