SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '69a83da71af70ced978b0186998245444443fd0a6a7221deb2a64d91b6eef1e8' 
  AND token = '4mlta+vuuZkBhYgMeHzOTIOZZ+3hsH7YQEA5P5nbkgg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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