SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '81b16ccab2dc6e8351afc88598d292c089f22ada612df1b73c06a05b60e57fe1' 
  AND token = 'QATqtWbYS+Li+/0g11ZdT/Y6Kzw0pUY1aNNAicoDEUc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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