SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c712519e38e9630cc785d3668a5a6c8006c558581ded930bc831f1d721582f87' 
  AND token = 'YjTOTwoPGl7eF4nPZrW23aPiktS69HtVfwnjYCABlvA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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