SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ac1b50c4a0164e5d5020af4128f9eca307fb01696818cb2105bd2c658ea8ca1' 
  AND token = 'OJx2fWL51uUDOe4V8VpU9tlP/66ZYlQft/cPJ4CGUlg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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