SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '63f3b04e7c5685265adaacc6d0923132ef010334a6a5e974b3b274979883f02c' 
  AND token = 'MSBijcVizA8lGX0e3OPZIsoLZNwy2xsUBdiaZGv2zqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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