SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e7a7a553e58d738b2f5105688241f6e247d1d5efd6b321ad80d509c7a2eecd4' 
  AND token = '38C//WAsuNfQLQXr0rFouJWft4GHOQPBnUdI80uj2mk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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