SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d866db0b351ab1cfa48beb60d7b6fbe3a719ff97d5fd0b499f522e55a7b43fb' 
  AND token = 'fJUvGSBvTJYgYgk9JduRVWRqC9EKvfw/N5V/X5yLHbE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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