SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df5439d925cc7f5f95aa89d400448ecb8662d9f3081c67155b3fdb9158741246' 
  AND token = 'E6BGlunpEKPcqSXj5XDIw2fGF0clSTBaCgpJd3ytQEc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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