SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f1541db99a847981e3fb790d49636919c09ee38f4952c3305e5d4d4f4a38cefa' 
  AND token = 'iMVen8lco+hTW9hasvFFP9MfpxsV+yzxkxsOsXmWNP4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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