SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '02ff9b3fea9c12f246066e4b0c399bd84a2f941be7394466dc614aa362f17b60' 
  AND token = 'MWD+WS+aCM1dmukJMQb27b7zPepVuKte9rf2801fULQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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