SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d7a6eb55d8bd6904270a00f43731f41c094349e1a5f59187af47f87d449db9c' 
  AND token = 'ur8d2v/MJZRaJWtqldvBRXPNFuC6+RPTuY0HZ7fjCn0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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