SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2fbe79f3a2ac3494a3a99ac8c0a36edc31e3bef8e9ae271a31d8e6b4728849c' 
  AND token = 'Ma78LlqlT8GjAWybCunrEAp4AwwPfXjvaoUFms3Qu5A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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