SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '679cba597beb0bebf4b16303341d626a827e502c129b9f70af68e36f178c70f4' 
  AND token = 'P/an9NPQX3qzBXPf2bJqtw/sbjJmcC+1/aB/qgsR+b8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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