SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ebea21bd57d85705e693edcfac0d5ff897755e1512f295163216471ff294448' 
  AND token = 'cNU2ZlDaKwIAe7cCoO4jG9OA5YVLcGKboMtcfQq5gqo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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