SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '5c238a87cf3620394a21e7a855089ca3990e74869b12ac3b3e7a628038d7b789' 
  AND token = 'd8Ed6r7cnoWtItYMsoDaoG6QzapbXJnktcJNFLZAEtg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00247

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}