SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4fd8e1d9a6406db26e65431ac834d7091d97d9652277d2d1c9afba279e5b9038' 
  AND token = 'KY7vfsslgBCFSWQfugu2n1b8ig6biehoyRPLFwo4O8c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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