SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3de8aac44cf6d3a5291b1ebd38f699a986f2a5ec9fef6c900e37e962e7e7cf6b' 
  AND token = 'CyumxFX+YpBASoF2sVzUnuUiBQJmn5fhjE7QYvJTTXQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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