SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7de61346a5defb32ff846db19c968446816b15b5ed0f3f14d915ca1f858872cb' 
  AND token = '1uaUk9NYJdqnMAnZIoq9/5trlSZUkP6bRUXkEQeOIAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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