SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e888d028173d02aaa9226fd3f1705a42381d2fdfe2a9037d1bdc8b907326d85f' 
  AND token = 'PRnRfs553RxSDOR1XvpGLnukr+NdUjZGK7eI7SY4M0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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