SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c820fd542f120fcff8d03268d420a58e751aaf1459ece7157cc12de45c999159' 
  AND token = 'ZYkBTJfjIplsrtEeffT9R37ZdIFU3fTCREGBIxwPM5U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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