SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '737c1564b2bdefdd61beb45394f08c34b00f930ff354b4eeee8f44dbaba09679' 
  AND token = '/uV2lUkPrXJPMBukgAD4ZAXu8SslhIPDEO/iedL0eKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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