SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1f491ec5eae452b79139ce24adc733126d09cff46fbaf6dc263fd9ce1b7e435' 
  AND token = 'jbKXZVRAookWv3+bfRL3zGc1V+pFcVE4jzKBZQbmdpY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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