SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79228d88a70c66198d0b9a57bcfb94e84eb84bbfac70a5a6733dd41e5ff8203f' 
  AND token = 'mYDkEludFaMjGTQkLEP1uLTtvFcxODkqbLotyCYeuDk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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