SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '756ed62788fbbda0b19ca1f4eb9aa7981913d0861ca415659d3e600867caaf1c' 
  AND token = 'PnPkQGrQganZc1W3YxqSci70EPg1ReFstz7HfLch17k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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