SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f770822aa5cb2834746af03f5d116fc674905259663d7da83f835e64a81f4c6' 
  AND token = 'tWtXa3tYRdqDaOC8zINC4NL6kC4NKM6IN72pc1sVDxs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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