SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f56ce7448dda93159db1b58388a87bb539141869c8ad2bc29486c1696a38477f' 
  AND token = '61epTRWcUjA50CKZGzFK4dXBUtvZLQlUvLfnNP7BXJI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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