SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd40c239fbbed856e734313304ca8d519154489aef77325855f3eb816565755c0' 
  AND token = 'HnCsqf42aAo7PalC9lTQB6hkbTMp6B/m1CFLOQA2yww=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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