SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ab8ce299c8ac4e147dac032a1be2bdfff2cb4267323a89d1bf8553c75500747' 
  AND token = 'lJqYJG6WYVSCSvVjLvPli44aYy/N81XCbFIjv9rfT+s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}