SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c6ef9c81838ffea15f9711ab5a311116b8410c08bfbf00a52367f6c1ba673ca' 
  AND token = 'b+/jS8jb0eNEkywhD/XQvpsuKaGIYU0BTqPghyCt1sM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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