SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3da873a6da0efaee8d18cddd83c42596a97fa5ca24b816310fc1044187bb0dc' 
  AND token = 'idDNqujz5wDHf4dKhgmRrdMLYxXr1PVfA5+ALlhVUVw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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