SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '383f9f2493e75e4bb03ed9d33a827df6de6a4bc996fa260926ff55de6e3f83d8' 
  AND token = '3HRZxRlgmRRyhZLvhrg7S96KpW53EM6EGd9857Dw7vY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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