SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eff1b297513d49773bc80cc7367638612e5056e210c402ac500293a4f702bb58' 
  AND token = 'bjZ+gug7dp8nwVqNV+0vk/drQ0LhMDDtbNL0dJc/HLw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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