SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1c9ba28e320ca3e361b56387458fef93d2b80b8ab70e78757d367a3262b7646' 
  AND token = 'ZN5zIzCDnGawWZ+qRp5GEnucHUjCOTKUM5zHrNTgi4I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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