SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7d309ab1fcfdebef75081e87f4a73d94e8ebc637607aebcb9217f764c61d26a' 
  AND token = 'HwtFSaXR4mGu2xGGxZ2lPUMRIXlGQAiuNwdl2qC4p88=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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