SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c9b53009cbc9a30c07a3d82d78fde01d1d8f0a43b563f63ef889f09d56d7ca3' 
  AND token = 'obQ4t+GftpXPBEPBnhSyU7a86Hi+Usd520e/cssa+pQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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