SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c948c76e9af871582dd190ccadfbe8969785b05696d4099217035bcfd78a023a' 
  AND token = 'OujAyBF/fHzd2TQwF3eKqlF6BdRWRw5rChi4KEBhEoM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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