SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5dcb246d4816bfeda0e96adfcfce6218641c0c2b48d73ea98f54e61f08da88b1' 
  AND token = 'hXBKIcj5nrsjvlI0wS+1KqGAM+KjME/7XlXtZNOKRIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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