SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3434a3c8cefb5463aca97f37bfcc803e84d8781e830057708cab6932fc082f7f' 
  AND token = 'qXwe813ppaM4psCZxKOJSPUEJedllarIm+XBAXcKwFM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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