SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e4ac85732239fbf3c3e63b31b5343932499042787ea0193794d165f650ab595' 
  AND token = 'vgZ0l4WOvw/MBufHsUDmD3uAwVhDc2b1zhWFZivd2oY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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