SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8d744534af01255d9b4492c9218bfa698b56a25a36fadc987a770b445d8bcc6' 
  AND token = 'FTse/qOlwP0NrG7dmd7OJF/A1vGafeVuLBx5mTVY/Ao=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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