SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36f78f2c8474389829afdcb0cb90bb77fe01b25847b477649d715f4ac352a313' 
  AND token = 'vHLPzrt7wUTMjd6q+OAqIKt3sx+uWA2XhatYw17Mch8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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