SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd440914a2f5ffa0ff125a6b9c1b1c28d88cfa65ecb71f8d799c00d7a7ed37736' 
  AND token = 'bser/ZdmHo3c8hOGr2vPIsEavQepja+nWAZVKcnVYgE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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