SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'cd0ca0248b40360c2532a3c02c46cf263c5f7678b47362aa72b9a9bb66be38fa' 
  AND token = 'Af3MbZZncgV5Kt3t5N3I08lxExYZkZIsfKrEqFimd5k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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