SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a169e329211323505916f9b86ce00b42842bd02ed3696e1cd16c25e78dc73b73' 
  AND token = 'VqRHfvf+dx6Kk6z3uzGQJO1oMBOBujAnvVPUuZM0S4w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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