SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12dc89a0f8c9ef11dfc7860d02abfd87c1edb8a3dc15036425a96ddbe776b755' 
  AND token = '6l+3+tPYmOFjkWqhpUFBEn6oAzODNh9dTfgjJ5kqPig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}