SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b34cdf03820488db3a0aff0b2152a2a259ed778d135c157b245cd3282fe98d9' 
  AND token = 'qU2NvdkF4JDB3HGHH/ee03QSbSgEIf+Nkb9KHtpQfCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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