SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f74af0f32355222e9503996314351c109d6ebea6025335079e4f4c40891db1f' 
  AND token = 'F4zbcUjIi5FAwaXyYMSFYbIrnwX8ZgGjmGE4ChbG42g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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