SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6793d8548069e143599b1856d138d1f15e95a24cdf54e64854cce268480c194f' 
  AND token = 'Flcu5pWZ05sGEzm1YLHPwqTxrivII3IVtdX2DxD8GlE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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