SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e787eda2ca80cedda606b79475b531992265aea517ac038573fd1b9e93bbf9a' 
  AND token = 'OoQmUpGUG8M7oSMiWuXYDAESBUsa1C4MsMhENzeRVxk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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