SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6f37005cdef9a32dbbab35d10ee1bdc8d18b8875acccac8851eb135700e998a' 
  AND token = 'mMx/+4WKa8TPTWRID9JsI+7o61ZbZJuWEkNRz95cuYQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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