SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd6f764429b5b9bee56dc832e8ecf8f5a5f28a30b2f44e55a05bf714ca5121da5' 
  AND token = 'WTvqVHx7ZEplBPJ5tRhSDRmsOzax9zwGjlAMTm4s3CQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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