SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ff6046d24a0e8d72b0904f8fc58968b206e1df7cfb7bc5b8e33731e3174ad7c' 
  AND token = 'V9rulLWvYqfd0tya3ExVORwrf8pxxFtp7VJnHyQiR3w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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