SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ef29d1281ce7506b2ec5c3dcda4a68c884127f1d366533bb8a849e46576d338' 
  AND token = 'Eonl6phiwCqldhXrmEIDsiMPFCguGN0/XB7jGsqAz58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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