SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '759b1a3c8f1f4fe9c89f44a60e68db55727506c0a337d6ecce61177728a837b0' 
  AND token = 'ufT+Q437gLwCGo8dP8Zgkha/5FbuvULqZMSIqkBVN/w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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