SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c64d4ddadae1d3bb2c641e471e39b5f8240c83863f10adbe906fef6e201608c5' 
  AND token = 'stgsJTY2yLgQiUr+8zYm7G/1nVgnOnZ9a7wjvLkQQ0U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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