SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '808a23924d04972788f75a0b35a371745b964fe227eca894215bf3d0ff7a89be' 
  AND token = '9tsflJs61lv89FgChr1Tz7CTPxUgBUSe2VFBQWXklLc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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