SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '351d05620ad1ba2bca3ac6cc0a3cc2a1e9749ead8d8122d7dfac9ff5f423c2af' 
  AND token = 'nBxYSzr9PlmoQEQr8CD+0fxD4O5ZW+RzyzSI2Jjnq9w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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