SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3f591f1214f929b893bb684a6e8d390b83f1aa9885f6e8e75bfae6bbb392532' 
  AND token = 'Kwo8M94POuk/CZcy/BUHLrhRMpucEjs2XwdHUrp5fE4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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