SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6611c36df799597e3bd8cd3222a443ad384adf18d79565cfc6d2047582d7e508' 
  AND token = 'DHsMwH1TwOjX2Jbp8skBukyrtRQIkGgC+vvWNXas+Kk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00563

JSON explain

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