SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4f665fd27a0ea860707618221edf334c42e853db4cade8e4495cb313f54d775' 
  AND token = '7kzV3pPcE2TSOiYUNEwDkGnIUZhTpvi11FvXd0crznw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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