SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '56eff56a13a0f4e80107bc3336b3e8d834c7799252a1c428bd73385255dea73f' 
  AND token = 'GGHSKHtvcqIQ/6pmj/Ek1rlev+z44OiRpRHpAoutvbM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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