SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8938ae5d6af75c9e4c7458887936648159c68647e4620dc645e0eb342ee9e7b1' 
  AND token = 'KFrQ2W9awVa2CMlXhgp+gItuwLYRYmbC9/vrGyp/bTM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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