SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6776005dec58baf42a453ad90562c15da343cfdf592630a7ed0038414b591ce' 
  AND token = 'eU/JxCOx7lZUQjWSdMQuUKQolVZTLMSwgIOZnHdsJHQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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