SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af5b7a4be76cc3188985ba59239fe87f0917324db30012506e01765efbe68566' 
  AND token = '6Ao+Hlw1UeQ30sbLArIuIgghiMFnPwNIqi8yny8OSoI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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