SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '473a3b33847696acab911c3a5ad9acae602738459353ac71dbdc462818f1c54e' 
  AND token = 'MVRHloY6LwcFm3mWy/w2LQKmlcFz3LHaoOUIcXnGw5o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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