SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bc67e458c357bdfd9947c995c1d856c0ee868778c5d606e1f4026f0cc420604' 
  AND token = 'sadFBOytP9nLlkid4klXIm9ZepFvJJZUijbb0Rul+Ug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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