SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ef801c73ae1caa61feb6805fdf454a8b54f0537e36a614dc7fcbf9f4208fd67' 
  AND token = 'y+xKUiTXZiVdNVVWWC4mTXwONGMopoeIQiDhnKsXzRo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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