SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2cbf5f7e6ed1005d29f76d6b3bffb61af784f471d9ce8998d093d6940ffc8db8' 
  AND token = '8G+Cyr2JVz//zA4eh1HFZ0mifcPvjFR7FMoY9DIn6VE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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