SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4d0bd609732462a7d6855aedee887fa06d756fa6e13094c9b254a4425b0c3a9a' 
  AND token = 'IEbCEYS3KlyY1f8lHVvt9dmnnjhB4VxCZguUYMtz10Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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