SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d9eb5a3fb3bb30aba76d92eb5d221754e0ba8ba41a1d8f663e135ac85c846a9' 
  AND token = 'mm+YMPSYo5574SpBiHKiwVeX4nWlFrrrg8IRfJIUvv0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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