SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf2157ddca1b31977eaa52099ce4be3bf3ba76d511cbadea938834aa5976b04f' 
  AND token = 'RN4uwNUJdHJMtKywQkbTHVS0RpPMBZhHASt0AMcEDRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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