SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3a6ea8a21715f5aa1ec4015141be0bb60d8d419a90638accc7b6125bb7d575d2' 
  AND token = '0vN/8bZRmNtmLrS+jZz0vzbemk4SN3rUew+/2rNoDrY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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