SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19db56387ff7948235e640ab0a06896e7184a87735620167c0be69c0fba520ac' 
  AND token = 'w/rglZ61B4qVGjUiVBzJYBoPZal0zgB84jIgAU5LJhU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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