SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9b6909bafc398cbde6590d411b0b67412f1284ebaf9a67aa2916ac9f01fac59' 
  AND token = 'IbFgeicyNqZiiC+Xzkf4Sc4Dtn/wzQ6bUfuBwgCZDfY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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