SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7db80fa3ea7f412632d360502610107cef0a4ffa826a19bac8d54945ce39210' 
  AND token = '0NpaVon8/7KYdc0nv8WjtosoCCfEwmJyumlhdj4MRDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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