SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66c1ba7b29a852014ea0e1bb35e97a8c30303f4bb2206f5424f240fa82ddb2a3' 
  AND token = 'S61dBWxv19qjzaGRPKtVC1CUBKRq2xzYOgGdvVl9F20=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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