SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ab27868cf31aefb73d46b4d39c0c57695ddd2d67b290e2a18504d833daf0793' 
  AND token = '+F+0vKmFzeidsV/6QA34sOkJO1ovgWEFq1L5XGgVcfU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00060

JSON explain

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