SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bcde90d61ddc0e4fa935bb3704afd41de17131da589388b9c9ef7cb204635082' 
  AND token = '9pnnvWKI36BY1dv/AU+712MjwvZ9gX54hT9W/ZYPHz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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