SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb39419381fd43b991ea544f4e83b5c9c406d1fcc25d0298e277afe6257dbd9f' 
  AND token = 'UlzXvvjVV3W8lYuL23YssweSzpwkjYIeY0Axs4CSkm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}