SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e4bb5416835771b961ed76b817b32b2bcef616d51c7dbbac3a8ecf81c7ddeb5f' 
  AND token = 'vqHzr+oS2ieI2vHuX9EDt9wtZzoqkT742ib9WCHFlKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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