SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bbc4f262489946ee0de2a590282f4288d4619bb56bf92951a20d1a3f29c3a583' 
  AND token = 'vG+7Z7/BPAyoe4TbzBgAIw0wrGGgqogCixEBmrIH+RY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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