SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb8f69a98af847c89083b3b2d008f4584d47704057b11bffacd8bf5f059d1cac' 
  AND token = '3ju5sTpGj10tR5UUKjQR09hBQoyYvJb3KEljTdWtOa8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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