SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bd7243a6938f9da7412aa0167df2bfc97d5d9e95a50c986e9c04cfeab5e2bb90' 
  AND token = 'jUJMwli2tgIRjcf86CnalXNMvpEPEfijaWtrqSSV6ro=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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