SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e271a31e135455212a6030599ecf4c9b05b614a05307dd3acda5ac889b646c2' 
  AND token = 'XO50HsAdmRTUDJK4eh4L/1+KIMkjiM3WYDJHmwCwFpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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