SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe36822331d968b056c9ed7404d6e4bf398a349e967fb246822a36fc348db9d0' 
  AND token = 'iFg5aZQ9mAE/VOtZeUgB+oZ5IxWaFWSC+VgHs66VNHM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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