SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3bd951476cf186821fbf86d35d7f5a159902d71427c05138e8e7058898a2dd43' 
  AND token = 'QkLkBovDxEhUs1XBQCjpYei1NxBFJombJ9huqclTwy0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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