SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c6a872fe6973a14295a5337f8712d26370a0f31c96a168875d8cd04742c0d59' 
  AND token = 'qi/uhEZByY/q6jilvQCfMAwHiuGex5aeoPNIS7LXfR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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