SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c878477ae4f81716337d9351b9eab3b78191f85b49e0ecf36526ff4cb870329f' 
  AND token = 'gJrFPAUyv5oN/Rjl3sERT29a/ECFVkFs4bK67v7mU9M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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