SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6bc32a2c31a6c1200ec87478997fee7f890cfece89e1594f509d38707014a03' 
  AND token = '3CQqUDhNyBoMscn7Rl+59eWpCxSe4CZmPPMEKBnoqtI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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