SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e55928152e4e1df72b8bc1863fdb07d7529d5256bfe980af04aeca4ab858fe44' 
  AND token = 'bdBmkmUvQ1H/TCYyT/gc4EWKG+stdABrwpwWhOVyL70=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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