SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9f5c47eb31249d6f1811e830de24b15148c1ffeb286383672b3a5658c880778' 
  AND token = 'UmlTOwzFkv6WpBxKtJzk4F/yaIMagnGibErQszVGmiQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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