SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb38f5eb6e4283f78802a9a36cc665d5d5b96a22a841151bf46d79a1b46d4c3b' 
  AND token = 'osDQAgeZnHVj3ZoSEkXg8fxjmTp62/QVCLlaUXj0H8w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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