SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6befa7d0ee795f2147c35d61f6c7f0ed9bfdd43c4ad770ca9171d920bcb2f3e' 
  AND token = '9cE3buPyGsseT3kzfLCfB8PqTGd0anXzVmszH+/dBtw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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