SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '835a76034ba0862c51d5f19ffec2772f33082a8d3f819518a227ec17b1ff74bc' 
  AND token = '2XBGsg4s6PDgBLXEBkJxIDWHA4GhqQZtPwNzW8hB+cY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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