SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9cee732373bd7cfb28120135fc4c815e747694ade6348d9ec65ed055546ba5b' 
  AND token = 'ASQOlCIrgx/xYJKX9T6nOJu8BB8oZ75U20Ma6JuztlY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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