SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7dd80e0185accb1aa057376bc1376422c10f3f15e6a66597a9575fabc0caf774' 
  AND token = 'QzWExs8nIIomfDVBzGyjH3HUfn8593nfm1mWcEVhtJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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