SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ce819699437a036209a39f0d8fe6fc877f4b74871c281752b6efb319d07ff259' 
  AND token = 'TSMDxndjjK/bvz9Ew7FiLjBi3WbNg4Sl+dC2eOHLJVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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