SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3a261bdeb783084fd3a48ea88aa1de08bb0e30e529003a03b5bbf23451547f5' 
  AND token = '2uEKD8Aw+pQc7/INUFrUhkTXrE9fg0lUbu0xiT/TPJk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}