SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52bf455a9fc3ec99efe4761f22ad52230d6484c1543b3d2bf3a7c8f7db40916b' 
  AND token = 'LQh8OmYmK/7J3/2PmfQpow7var6NdeJqtmyM//YcfU4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}