SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f683cefcdc624cf5854085776d972ed2cf4c27552236ec92776c8be8771a66c' 
  AND token = 'EfOscvU4kni9NHNr5ucO9ALnhfHomOJacWSwD2BKfgY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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