SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d7ba54f0ff92abb28290613504c1f8e4baf3df489fd3c1bc1d134d6b3fa50ed' 
  AND token = 'P94goGrVjmvnrfl500nAXjsbGL88b6kXx4fhnFQo6l8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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