SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '852b4c8360297bf9ffb98ba8e998500982bd06bed66ea028b6bb7fcd62828d4c' 
  AND token = 'jywiM/eRDvbdKYDXL8KkqNdJfS5oIyMHf9w5AxUpRVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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