SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b2abbddc5290959714446710bf1e720b1e41301bef1ecbbbbc8b7b4f9bbf0ab1' 
  AND token = 'MdpwZa+9fUIEPLW66dohdrWV6kaFSfgYG1gEhPCj1ms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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