SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bec40c823f1a409df2a621b4e3db1b0e34c8cce8dd98a7876f0ea76d7f3ad339' 
  AND token = 'AiG2ZNXVZCGTHeyStUVOvHjzJ16hAgTfmiAIF+BUoms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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