SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd814edf7935accb4e9d354ffd9dda299c1eb8bfa767b18d4ddce00aa721dc138' 
  AND token = 'QOk4BGksGeFKulk7C+40FoXlOBaZ/sEtfH7mUkidMxw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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