SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c8cba5657ca6f5f4d9270ab169fd121d0067a0efdea212b561dfb20f50f80990' 
  AND token = '0JWgz3L9HuIgPltCSMssxIs/t04gAe4IhG+cQEcKHwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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