SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b6de2916c2084ede2805ff51dc8da8cb63173ff18db3b5e35f16099b66e91b3' 
  AND token = 'F3ilFQqPRejPnZu8g5Q7jyGkBgmUJdzzx6IK33hKLuc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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