SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29c5f4141a564b8a1435755fcb3ffebda7e559581a5298af72c920bce40156f4' 
  AND token = 't6qxlBrHm6nKNZ5bAHihWMBsO7BYQ3wYFDtpDVKFNAw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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