SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ec682fcd0a62a1d9e18e9a88ee1e3c093b7835fd7a5f028fb2a0aa951e2871a' 
  AND token = 'bAvDvfkwsbDSOytVAHJOZTbWWaR0XvMycFnerh9Tu2s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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