SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4d21a3a3689018c9843ccb5fcc02076d3e9d6fdb5463053ce39339c300b6ef1' 
  AND token = '6KlejjKDgbwMSzWHyTVs2G1jL//S6Prq5G6aGmKNa7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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