SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77f1ef09343751a59849d64549d7b931b505621d6f259d90176797e31c8fd341' 
  AND token = 's5/Z8RxV/2vSVdJTAfmiMQJzLpGL7TxPQjpquQR9z5o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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