SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6796be04e33c6b98dc2006b5350539fc78a51443f3ddff582f3d33ed37cbf565' 
  AND token = 'PCS69Ko8GBcOdNIaSiTzhpFpmRS7QMDq3y0uvUG77GE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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