SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b57af301d0ea24144b7a31175bb5f2713d21086711f0be8c9f862599760d26cf' 
  AND token = 'AWE+hxpxm7XlHsJXsO4YhDbiKDazR74dSlCZYMeCoXg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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